Round two for the trendsetter among modern off-roaders: Mercedes-Benz presents the new M-Class. With state-of-the-art technology such as three powerful new engines, the seven-speed automatic transmission 7G-TRONIC fitted as standard, the now even more effective four-wheel drive system 4-ETS, AIRMATIC air suspension and the anticipatory occupant protection system PRE-SAFE®, the M-Class is set to reaffirm the Off-Roader’s leading position in a fast-growing market segment which Mercedes-Benz created with the preceding model in 1997. After its premiere at the 2005 Detroit Auto Show, the new M-Class will be introduced onto the US market in the spring of 2005 and in Europe in the summer.
You need look no further than the design of the new M-Class, with its beguiling blend of strongly contoured surfaces and taut lines, to admire the majestic character of the second-generation Off-Roader. The swept-back windscreen, striking front wings and rising shoulderline of the new car set the unashamedly sporting tone, a theme developed by the proportions of the body: the new M-Class is 150 mm longer (now 4780 mm), 71 mm wider (now 1911 mm) and 5 mm lower (now 1815 mm with roof rails) than its predecessor. The wheelbase has grown by 95 mm to 2915 mm.
Three of the four engines available for the 2005 model are new and outstrip the output and torque of the power units for the outgoing model to the tune of up to 38 percent. Cutting-edge drive-system technology and impressive aerodynamics (the Cd value is down to 0.34 from the previous 0.40) combine to cut fuel consumption by as much as ten percent.
A new V6 diesel engine, available with two different outputs, is celebrating its premiere. It features third-generation common-rail direct injection and the latest in piezo injectors. The unit in the ML 320 CDI delivers 165 kW/224 hp and places a maximum torque of 510 Newton metres on tap from 1600 rpm. Also on hand to offer the twin benefits of six-cylinder comfort and dynamism is the new ML 280 CDI, serving up 140 kW/190 hp and a peak torque of 440 Newton metres. The diesel models burn just 9.4 litres of fuel per 100 kilometres (combined consumption), making the new M-Class one of the most economical off-roaders in its class. Another new arrival is the V6 petrol unit powering the ML 350, with 200 kW/272 hp and a maximum torque of 350 Newton metres. The engine range is headed by the eight-cylinder unit in the ML 500, which now has an output of 225 kW/306 hp.
The unique seven-speed automatic transmission 7G-TRONIC is fitted as standard in all variants of the new M-Class. Intelligent shift management allows the transmission to make optimum use of the engine’s enviable reserves of power, while making a major contribution to fuel economy. 7G-TRONIC can now be operated electronically using a gearshift lever positioned close to the steering wheel, a new system which Mercedes -Benz calls DIRECT SELECT. Additional steering- wheel gearshift buttons enable the driver to glide manually through the seven gears.
Ready for rough terrain: the off-road package with AIRMATIC
Mercedes-Benz has taken the permanent four-wheel drive and 4ETS traction systems to the next level by incorporating additional functions such as Downhill Speed Regulation, Start-Off Assist and the ff-road ABS system. The M-Class can be ordered with two different variants of the four-wheel drive system, allowing it to meet the varying requirements of off-road drivers: in addition to the basic version, the new Off-Road Pro engineering package is optionally available; it enables the M-Class to master even the toughest routes across rough terrain. Its primary features include a two-speed transfer case with an off-road ratio, manually or automatically selectable differential locks (100 percent) between the front and rear axle and on the rear axle, and a modified version of the AIRMATIC air suspension system tailored to off-road driving, which can raise the ground clearance by 110 mm to as much as 291 millimetres and the vehicle’s fording depth to a maximum of 600 millimetres.
The air suspension also significantly improves ride comfort, which is why Mercedes-Benz offers a road-going version of this technology as an option. AIRMATIC teams up as standard with the Adaptive Damping System (ADS), which adjusts shock absorber response to suit the current driving situation. All this accelerates the M-Class into a new dimension in driving dynamics and ride comfort.
Mercedes engineers have also redeveloped the front and rear suspension of the M-Class: the double-wishbone front suspension makes a significant contribution to reduced road roar and tyre vibration, ensuring impressive driving dynamics with its raised aluminium wishbones. The new rear axle has a four-link suspension system.
Standard-fitted light-alloy wheels and wide 235/65 R 17 (V6 models) or 255/55 R 18 (V8 model) tyres emphasise the sporting pedigree of the new M-Class.
A new era in safety: PRE-SAFE® makes its debut in this vehicle class
The Mercedes-Benz M-Class also sets the pace for other off-roaders in terms of safety. Its occupant protection system is underpinned by a self-supporting body structure with large deformation zones in the front and rear ends, and a wealth of state-of-the-art technology from the luxury class as standard. This includes adaptive, two-stage airbags for the driver and front passenger, front sidebags and windowbags, as well as belt tensioners and belt force limiters for all seats. In the event of a rear-end collision, the newly developed NECK-PRO crash-responsive head restraints (optional) provide additional protection for the driver and front passenger.
With the option of adding the anticipatory occupant protection system PRE-SAFE® to the mix, the new Mercedes Off-Roader raises the bar in its class. This multi-award-winning technology provides a reflex response to critical driving situations where an accident threatens to occur, preparing the car and its occupants for an impending collision. PRE-SAFE® acts in advance to pull the driver and front passenger seat belts taut, bring the fore/aft setting and the cushion and backrest angle of the electrically adjustable front passenger seat (optional) into a more favourable position and close the sunroof (optional) if there is a risk of the vehicle rolling over.
It is by forming an unparalleled synergy of active and passive safety that PRE SAFE® can prepare the car and its occupants for a possible impact. The system is linked to the anti-lock braking system (ABS), Brake Assist and the Electronic Stability Program (ESP?), whose sensors identify dangerous driving manoeuvres. Mercedes-Benz also uses these data for anticipatory occupant protection.
The new M-Class also boasts exceptional long-term quality – another Mercedes hallmark. The fully galvanised body is given extra protection from corrosion by means of an organic coating at specific points. Structural areas subjected to high stresses are cavity-sealed, and folds are seam-sealed. Large plastic underbody panels eliminate the necessity for conventional PVC undersealing.
Part of the standard specification for the Off-Roader is a new type of paint finish employing nano-technology, which made its series-production debut in Mercedes-Benz vehicles. Offering significantly improved scratch resistance compared to conventional non-metallic or metallic paint finishes, nano-particle clearcoat provides a noticeably enhanced sheen.
Like all Mercedes passenger cars, the M-Class also comes with the 30-year MobiloLife mobility and value-retention warranty.
On a par with the luxury class: greater comfort and more space
The interior of the new M-Class also exhibits typical Mercedes quality, thanks to higher-quality materials, more pleasant touch and feel characteristics and significantly improved spaciousness for all the vehicle’s passengers. For example, at 880 mm, the distance between the front and rear seats is 15 mm greater than that in the outgoing model, achieving a level more familiar in a luxury-class saloon. Knee-room for the rear passengers has been increased by 35 mm and elbow width by 32 mm. M-Class customers can select the seats for their new Off-Roader to suit their personal comfort requirements. In addition to the standard-fitted front seats with electrically adjustable height, backrest and cushion angle, sports seats with specially contoured backrests can also be specified.
Up to 2050 litres of load capacity offers ample space for luggage and sports equipment
The cushions and backrests of the rear seats are split 60:40 and can be folded down. Removable cushions can be ordered as an option, creating a level loading surface stretching 2.10 metres in length through the rear of the car. The maximum load capacity is 2050 litres (VDA measuring method), significantly more than comparable competitors.
The proven EASY-PACK system makes the boot area of the M-Class easier to load and unload. Among other features, it can be optionally supplied with an electrically operated tailgate and a package designed to secure items safely in the load area.
State-of-the-art support systems familiar from the luxury-class Mercedes models help to relieve driver stress, enhance comfort and further improve safety. The M Class is optionally available with the newly developed multi-zone THERMOTRONIC automatic climate control system, the PARKTRONIC parking aid and the COMAND APS control and display system with pan-European DVD navigation. Bi-xenon headlamps with the Active Light System and cornering light function (optional) enhance driving safety during the hours of darkness.
Wider, longer, lower – in brief, this is the formula for the exciting appearance of the new Mercedes-Benz M-Class. Although the wheelbase and track of this successful SUV (Sports Utility Vehicle) by Mercedes-Benz have been enlarged, the new M-Class makes a very compact and concentrated impression. As a careful evolutionary process, the designers have given it even more dynamic but stylish lines. The result is a decidedly sporty and athletic character with a clear, powerful message.
The muscular impression is created primarily by the stylish interplay between the soft contours and angular elements which give the vehicle’s body its powerful structure. Numerous surfaces are delineated by sharply-drawn, muscular lines. At the same time these contours are extremely modern, give an impression of power, precision and solidity and create an interplay between light and shade which appeals from any angle. Moreover, many of the design touches clearly underscore the off-road qualities of the new M-Class.
Front end: striking features
The front end of the new M-Class sends out powerful signals. Its striking radiator grille leaves no doubt as to the fact that this is a vehicle with a personality of its very own which will accompany its owner through any situation that life holds in store. This impression is conveyed by the robust appearance of the grille, which is characterised by its three wide louvres with pronounced, angular air apertures integrated into them as well as by the Mercedes three-pointed star in the centre. The strong horizontal lines of the radiator also emphasise the width of the vehicle.
The grille is emphasised even more by a continuous, surrounding chamfer, which also delineates the bonnet and creates a self-contained design feature. Two ventilation grilles on the bonnet, which each feature three hallmark Mercedes fins, underline the sporty qualities of the new M-Class.
The restyled headlamps likewise make the new M-Class appear wider, as well as adding a new highlight to their appearance: the clear lenses now reveal the latest headlamp technology in three shiny, individual chrome tubes. Their lower edge is defined by a narrow indicator band, which runs across the entire width like a shiny glass rod and adds another striking focal point to the front end.
The impression of robustness is intensified by the bumpers, whose lower section has a dark colour contrast, clearly indicating the high ground clearance which is so typical of an off-roader. As a further interesting detail, the bumpers feature an aluminium-look underride guard with large, square apertures. Separate frames on the right and left accommodate either fog lamps or the combined fog lamps/cornering lights, a positioning that once again emphasise the width of the new M-Class.
Side aspect: dynamic elegance
The new M-Class suggests strong, forward-flowing energy when viewed from the side. This is due to the overall proportions and the rise of the major body lines towards the rear – including the shoulder as a harmonious extension of the front wing, the waistline, rub strip and side skirt. At the same time the body is visually elongated and injected with dynamic elegance by a pronounced contour running from the headlamps, along the A-pillar and roof frame and back to the tailgate.
The shoulder tapers gradually towards the rear and ends satisfyingly in an aerodynamically formed airflow breakaway edge. The C-pillar is positioned at the highest point of the shoulder as the visual centre of power. As in the preceding series, the C-pillar of the new M-Class is slanted forwards but now has an even more flowing line, allowing it to establish itself as a distinctive characteristic feature of the M-Class.
The pronounced edges of the muscular wings stand out from the basic shape of the bodywork, indicating not only power but also precision and sure-footedness, while effectively emphasising the large wheels. Depending on the equipment line, the new M-Class is fitted with 17-inch to 19-inch light-alloy wheels whose unbroken surfaces and stabilising chamfers suggest solidity and spottiness to further accentuate the four-wheel-drive character of the M-Class.
Rear end: pronounced contours
The rear end is characterised to a large degree by the extended, curved rear window, which merges with the rearmost side windows to form a wide, panoramic surface and which combines together with horizontal edges to suggest powerful forward motion while effectively emphasising the vehicle’s width and visually reducing its height. This impression is reinforced by the tailgate with its high-quality chrome handle and by the powerful, high-set rear bumper, which has the same two-tone paint finish sported by its counterpart at the front and whose toothed design and underride guard are perfectly in keeping with the off-road nature of the M-Class.
Especially when viewed from the rear, the wide track and pronounced wheel arches make an extremely sporty impression as well as lending sturdiness to the vehicle’s appearance. A third brake light integrated into the prominent rear spoiler rounds the tail off at the top and produces an even more powerful profile.
Interior: comfort with elegance and attention to detail
The interior of the new M-Class is characterised by self-assured elegance with calm, unbroken surfaces, meeting the requirements of discerning customers looking for an SUV that is able to accompany them through any situation in life with serenity, absolute reliability, comfort and charm. The unique atmosphere inside the new M-Class is also heightened by interestingly contoured features and high-grade materials which are finished with craftsman-like precision and attention to detail.
Drivers of the new M-Class are seated at a new four-spoke multifunction steering wheel whose two lower spokes feature an appealing aluminium finish. Behind it there is a broad dashboard which is horizontally divided into an upper and lower section in terms of both form and colour. Circular ventilation outlets are arranged in the centre and at the left and right extremities; their chrome surrounds are reminiscent of the engine pods on an aircraft wing.
The upper section of the dashboard arches powerfully over the instrument cluster, which has two slanted tubular binnacles for excellent legibility and a sporty look. An added touch of elegance is provided by their fine chrome surrounds.
The uncluttered, clearly arranged centre console features easily accessible and thoughtfully positioned controls and displays that combine ergonomic perfection with supreme precision. Various infotainment systems are also located here – from a CD radio to a CD radio with integral navigation or the latest COMAND system with DVD navigation and a large colour screen (optional).
The centre console extends into the prominent tunnel covering with its stowage compartments and integral cup holders. Also to be found here are two forwards-pointing, attractively styled handles which not only echo the principal lines of the overall design, but also provide a firm hold when driving off-road.
The two-tone colour scheme of the interior along the horizontal dividing line is also applied consistently throughout the centre console, tunnel covering and door panels. These panels are concave in shape at elbow level, thereby increasing elbow room and adding an extra-special touch of style to the interior with their pronounced contours.
Depending on the chosen specification, the centre console and doors feature a wood, wood/chrome or aluminium trim. The trim strips in the door panels are slanted forwards to echo the dynamic lines of the exterior.
The interior of the new M-Class is characterised by precision-crafted, high-quality materials, such as the soft leather of the armrests, as well as decorative topstitching and surfaces which are pleasant to the touch. The result is a harmonious ambience of elegant refinement. Three colours – black, alpaca grey and cashmere beige – are available for the interior appointments of the new M Class. These can be combined with two non-metallic and nine metallic paint finishes.
Aesthetics and ergonomics - these are two of the most important aims guiding Mercedes designers and engineers when they create a new vehicle interior. The new M-Class reaffirms the high standards of the company where these disciplines are concerned: with pleasing contours, high-quality materials, attractive colour combinations and an unmistakable attention to detail, the designer team has created an appealing vehicle which captivates at first sight and invites one to climb in.
The fact that this first sensual impression is not disappointed is due to a new, intelligent dimensional concept which brings comfort and ergonomics to a new, higher level. In other words, the occupants immediately feel comfortable, protected and safe. The spaciousness, freedom of movement, seating position and operating convenience already make a promise that the new M-Class keeps for mile after mile: the perfect driving experience.
The basic parameters that allow a harmonious interaction between man and machine are the interior dimensions that determine the spatial comfort of the occupants: the distance between the seats, knee room, elbow room and shoulder room. In these respects the new M-Class has literally gone up in size compared to the preceding series:
- The distance between the front and rear seats – an indicator of the passengers’ freedom of movement – has increased by 15 mm to 880 millimetres, the level encountered in the luxury class.
- Thanks to the longer wheelbase, the knee room for passengers in the rear has increased by 35 millimetres.
- The elbow room for front-seat occupants has increased by 30 millimetres, the shoulder room by four millimetres.
- The elbow room in the rear is now 1520 millimetres, 32 millimetres more than in the preceding series. The rear shoulder room has increased by 13 millimetres
Front seats electrically adjustable for height, inclination and backrest angle
When planning the dimensional concept of the interior, Mercedes engineers took care to ensure that both male and female drivers of any body size would benefit from an ergonomically favourable seating and driving position. Accordingly the seats have an overall fore/aft adjustment range of 340 millimetres and a height adjustment range of 90 millimetres, and the steering wheel is also individually adjustable. The driver is able to adjust the steering wheel height by 25 millimetres in each direction, and adjust the reach by moving the steering column forward by 25 millimetres or pulling it out by 35 millimetres.
Electric motors help the front seat occupants find the most comfortable position: the seat height and the angle of the seat cushion and backrest are electrically adjustable as standard. Only the fore/aft adjustment is by mechanical means. A fully electric adjustment function for the seats, head restraints and steering wheel – also with a memory function – is available as an option.
Seating comfort is provided by foam cushions with precisely calculated zones of varying hardness: the foam material is of a harder consistency in the raised seat bolsters to give the driver and front passenger more lateral support on bends, while the softer configuration of the seat cushions ensures an even distribution of pressure and therefore a high level of comfort. The foam sections are held in seat cushion trays which are in turn suspended on steel springs. The backrests consist of a robust sheet steel frame with tensioned spring elements which support the foam sections. A manually adjustable lumbar support is integrated into the backrest of the driver’s seat. Both front seat backrests are equipped with sidebags as standard, which deploy in the event of a lateral collision and supplement the protective effect of the windowbags, which are likewise standard.
Fully-folding rear seats with a 60 : 40 split
The rear seat cushions are also based on the latest plastics technology, and offer considerably more comfort than the preceding series thanks to thick foam padding on the seating surface. There are three height-adjustable head restraints and three inertia-reel seat belts with belt buckle tensioners and belt force limiters to ensure the safety of the occupants. Sidebags can be integrated into the rear-seat backrests as an option.
The rear seats in the new M-Class have a 60 : 40 split; the wider section is on the left side and incorporates a folding armrest with a stowage compartment and cup holder. The rear seats can be folded forward very easily: the seat cushions are first individually or jointly pivoted forward to a vertical position behind the front seats. The backrests are then folded forward together with the head restraints: these do not need to be removed. In conjunction with the EASY-PACK system both seat cushions are removable as an option, extending the level loading floor from 1710 to 1905 millimetres.
With the rear seats in their normal position the load compartment is 1063 millimetres in length and 1027 millimetres in width. This provides enough space for a pram, or at least six crates of bottled drinks or two large golf bags. Those requiring more space for luggage or recreational equipment have many ways of adapting the interior of the new M-Class to the transport task in hand.
The largest cuboid that can be accommodated in the rear of the new M-Class has a volume of 1056 litres. If the front passenger seat is moved to its most forward position, the load compartment length is increased to a maximum of 2100 millimetres. Six chrome lashing rings for securing the cargo are standard equipment in the Mercedes Off-Roader.
Easier, more convenient loading with EASY-PACK
The well-proven EASY-PACK system (optional) by Mercedes-Benz makes it easier and more convenient to load and unload the new M-Class. This includes a hydraulically powered tailgate which is opened or closed by pressing a button in the driver’s door, or by remote control. The optional load compartment cover with an integral safety net is also part of the new EASY-PACK system.
In addition, Mercedes-Benz has developed numerous components which allow the secure stowage of large and small items in the load compartment, and reliably prevent luggage, shopping bags or other objects from sliding around when the vehicle is on the move. The EASY-PACK load-securing kit is based on aluminium rails on both sides of the load compartment floor, to which a telescopic rod can be attached on special mounting bases to create a crossways or diagonal division and/or a load lashing belt with a width of 95 millimetres and a length of 1000 millimetres can be anchored.
Multifunction steering wheel and two-section central display in the cockpit
The new multifunction steering wheel with operating buttons and the attractively contoured instrument cluster with its central display are the most important components of a modern operating and display concept which both informs and assists the driver.
With help of the standard-fitted multifunction steering wheel, the driver is able to operate the radio and car telephone by thumb pressure or access important information which appears in the central display of the instrument cluster. In addition, more than 50 individual settings can be programmed at rest in this convenient manner – from a digital km/h display to automatic door locking and the speed limit for winter tyres. Once selected, these functions are constantly active and require no buttons to be pressed or any other manual intervention.
The attractive and clearly arranged instrument cluster with chrome-embellished dial instruments for the speedometer and clock (left) and the rev counter and fuel gauge (right) keeps the driver informed about the most important vehicle functions. The different red and yellow indicator lamps are distributed over the surfaces of the two dial instruments, but only come to the driver’s attention when the engine is started or when they are needed. The central display is located between the two cylinders of the dial instruments. Its upper section shows the information and displays selected using the multifunction steering wheel, while depending on the individual settings, the lower section shows the outside temperature or vehicle speed, the position of the automatic gearshift and the current gear.
The interior door panels also form part of the operating concept. This is where Mercedes engineers have positioned the switches for the standard-fitted power windows, exterior mirror adjustment and remote control tailgate (driver’s door).
The layout of the units and controls in the centre console is according to ergonomic principles, with priority given to the importance of the relevant functions, the frequency of use and visual considerations. This means that depending on the level of equipment, the radio or navigation system is in the most easily visible and accessible position. This is followed by the control panel for the standard THERMATIC automatic climate control system or the optional Multi-Zone THERMOTRONIC system, which features well-positioned and attractive rotary controls for manual temperature selection (right). The lower end of the centre console is occupied by switch panels with buttons for off-road functions, Downhill Speed Regulation and the hazard warning lights, as well as for optional features such as heated seats, differential locks and the low-range function.
Thanks to the innovative DIRECT SELECT gearshift on the steering column, which makes it possible to dispense with a conventional automatic selector lever, the tunnel covering in the M-Class has sufficient room for a spacious stowage compartment and a cup holder. Both are concealed by lids which pivot upwards slowly at the touch of a finger. There is also a spacious stowage compartment in the padded armrest between the front seats, and its upper section will accommodate a mobile telephone. The rear end of the tunnel cladding takes the form of two separately adjustable ventilation outlets for the rear.
Sophisticated interior lighting concept
To ensure that the occupants of the M-Class feel just as at home at night as during daylight hours, Mercedes engineers have developed a sophisticated lighting concept for the interior. This not only includes indirect illumination of all the major switches and controls in the centre console, but also reading lights for the driver, front passenger and rear seat occupants as well as lights in the front footwells which, like the other interior lights, automatically dim when the doors are closed. Ambient lighting in the exterior mirror housings and courtesy lights in the doors ensure that passengers are able to enter and leave the vehicle safely in the hours of darkness.
Mercedes customers are able to shed even more light on things with the interior lighting package. This optional item supplements the standard interior lighting with illuminated door handle recesses, footwell lights in the rear and ambient lighting in the tailgate. The stowage compartment and cup holder in the centre console are also illuminated.
THERMATIC automatic climate control as standard
The standard THERMATIC system ensures a high level of climatic comfort. In "Auto" mode this automatic climate control system varies the blower speed depending on the individual temperature selection and automatically controls the proportion of recirculated air at high ambient temperatures to cool the interior more rapidly. The driver and front passenger are able to select their preferred temperature individually by means of attractively styled rotary controls. Red LEDs display the selected values. Buttons for ventilation of the rear and residual engine heat utilisation are integrated into the control panel on the right. In the centre between the control units there are buttons for manual adjustment of the blower speed, the defroster function, the heated rear window, air recirculation and airflow distribution.
Efficient ventilation of the interior is assured by a total of eleven ventilation outlets in the instrument panel, footwells and tunnel cladding. In addition to the large defrosting vent aimed at the windscreen the instrument panel features four prominent circular vents which can be individually adjusted by the driver and front passenger; these can be swivelled and the airflow can be variably controlled by a selector wheel. Passengers in the rear have a central floor-level vent for the footwells and two swivelling, adjustable vents in the tunnel covering.
The tunnel function, as it is known, is a further special feature: if the driver presses the air recirculation button down for a longer period (approx. two to three seconds), this not only closes the air recirculation flap in the air conditioner but also any open windows and the sliding roof. If the button is depressed again they return to the previous position. Mercedes-Benz equips the CDI models in the new M-Class with an additional PTC heating element. This is located behind the heater heat-exchanger for the air conditioning system and switches on as required – depending on the ambient temperature – to warm the interior quickly after starting the engine.
Multi-zone THERMOTRONIC with a booster fan for the rear
With the multi-zone THERMOTRONIC system (optional, standard in the ML 500) the new M-Class again achieves a level of climatic comfort on a par with the quality experienced in a luxury saloon. This automatic climate control system supplements the standard THERMATIC with additional functions which mainly benefit passengers in the rear:
- A booster fan in the tunnel covering enables the airflow to the rear to be independently adjusted.
- The temperature and air volume for the rear can be individually adjusted by means of a separate control unit in the tunnel covering, allowing efficient multi-zone climate control.
- The system also automatically controls the air distribution for the driver and front-passenger sides as well as for the rear.
Sensors supply the THERMATIC microprocessor with current data for the interior and ambient temperatures, the position of the sun and the level of humidity. In conjunction with an infinitely adjustable refrigerant compressor, the dew-point sensor measuring the moisture level enables the automatic climate control system to be precisely and economically controlled as required. An activated charcoal fil-ter absorbs airborne pollutants and prevents odours from disturbing the vehicle occupants. If the carbon monoxide and nitrogen oxide concentration in the incom-ing air exceeds a certain value, the air conditioner automatically switches over to air recirculation mode thanks to a special pollution sensor.
The control panel for multi-zone THERMOTRONIC uses a display to show the temperatures which the driver and front passenger are able to select using the ergonomically designed rotary controls, as well as the current blower speed. The "Mono" button in the left-hand control makes it possible to synchronise the settings for the driver and front-passenger sides as well as for the rear, and to transfer the temperature selection to the left-hand rotary control.
Choice of two navigation systems
Top entertainment and outstanding acoustic pleasure are also catered for on board the new M-Class. In standard trim the Off-Roader leaves the assembly line equipped with the Audio 20 car radio, which has FM, MW, LW and SW reception and an integral CD player. Excellent operating convenience is assured in conjunction with the likewise standard multifunction steering wheel: without taking his hands from the wheel, the driver is able to adjust the volume, for example, or activate the station search function to select a different radio station. The unit also features a keypad which enables telephone numbers to be entered if it is networked with a car phone or mobile phone.
Mercedes-Benz offers an optional high-performance system with an integral twin-tuner FM receiver, a CD player and a directional arrow navigation system with dynamic route guidance based on RDS-TMC in the form of the Audio 50 APS. The unit features a 4.9-inch graphic TFT colour display. The navigation CD contains the road networks of the major European countries, and the integral CD player is able to play music CDs during the route guidance process. The other radio and operating functions are identical to those of the Audio 20 unit.
COMAND APS with off-road programme
The top-of-the-line audio system is COMAND APS (optional), which combines a radio, navigation system and CD player. The centrepiece of this unit is a large colour display (6.5") in the latest TFT technology, with an excellent resolution and colour reproduction. A navigation DVD is provided which contains the European road network and tourist attractions. Route guidance is by means of a colour map in the COMAND display, directional arrows in the central display of the instrument cluster and verbal information. After route calculation the navigation DVD can be removed and the system used to play music CDs. In this case the navigation system operates with directional arrows. For radio reception the unit is equipped with an FM/RDS twin tuner, and will also receive long, medium and short-wave programmes.
In the M-Class, COMAND APS includes a special off-road menu with helpful information for drivers travelling off the beaten track: the current course with a compass function, the altitude and the steering-wheel angle.
All the Mercedes radios available for the new M-Class feature a speed-dependent volume control function: from approx. 20 km/h the volume is gradually increased to suit the relevant driving situation. An aerial diversity function, which ensures the best possible reception by switching between the roof aerial and two FM aerials in the rear window, is also standard equipment with the Audio 20, Audio 50 APS and COMAND APS units.
Surround sound from eleven loudspeakers and a sub-woofer
Eight loudspeakers are connected to the Mercedes audio systems as standard. An even more sophisticated set is available as an option: a surround sound system with eleven loudspeakers and an additional sub-woofer. This system is precisely configured for the acoustic conditions in the interior of the Off-Roader: a microphone registers the prevailing background noise so that the microprocessor is able to adjust the volume and tone precisely, thereby ensuring consistent listening enjoyment.
As a further option in conjunction with the Audio 20, Audio 50 APS and COMAND APS units, a 6-disc CD changer is available which is housed in the glove compartment. The CD changer is also MP3-compatible.
The new M-Class also shows its strengths with three newly developed six-cylinder engines. The V6 power units comfortably better the engines of the preceding series in terms of both output and torque. The well-proven eight-cylinder unit in the top-of-the-line ML 500 also generates 10 kW/14 hp more in the new M-Class, while the maximum torque of the V8 has been increased by a further 20 to 460 Newton metres.
Despite the higher output, fuel consumption remains at the same level as the preceding series. In the new V6-model ML 350 it is even 10.4 percent lower than for the previous ML 350. All the engines in the new M-Class meet the EU-4 limits, and by virtue of their ultra-modern technology the diesels even manage this stringent standard without a particulate filter.
More output and even higher torque translate above all into greater driving pleasure. In the case of the new M-Class, the measured performance data already show what Mercedes customers can expect from the Off-Roader in future. Two examples:
- The ML 280 CDI (140 kW/190 hp) accelerates from nought to 100 km/h in 9.8 seconds, and is therefore over two seconds faster than the previous ML 270 CDI. Top speed has increased from 185 km/h to 205 km/h.
- The ML 350 (200 kW/272 hp) takes just 8.4 seconds to accelerate from nought to 100 km/h – 0.7 seconds less than the previous ML 350. The maximum speed of this six-cylinder model is 225 km/h (predecessor: 205 km/h).
All the engines for the new M-Class are combined with 7G-TRONIC as standard, the world’s only seven-speed automatic car transmission. This is able to take full advantage of the high output and torque potential of the six and eight-cylinder power units in any driving situation.
A new dimension of diesel driving pleasure
In 2005, Mercedes-Benz is opening a new chapter in its tradition-steeped history of diesel engine development, underlining its leadership in this field with a newly developed V6 power unit. This engine combines all the current and trailblazing technologies in diesel engine development - from the mechanics and thermal/flow dynamics to the electronic engine management and emissions control. This guarantees outstanding results in terms of output and torque characteristics, economy, exhaust emissions and smooth running.
The new V6 engine replaces the previous in-line five-cylinder unit of the ML 270 CDI. In the new M-Class, the new CDI engine is available in two output ratings: 140 kW/190 hp and 165 kW/224 hp.
The world’s first aluminium V6 diesel engine
More output, more torque and lower exhaust emissions – the engineers at Mercedes approached the main objectives of their development work in various ways. Take lightweight construction, for example: owing to an intelligent choice of materials and innovative production methods, the DIN weight of the unit has been reduced to approx. 208 kilograms or roughly the level of the in-line five-cylinder. The power-to-weight ratio of the V6 engine is a remarkable 0.79 kW/kg.
As a world first, Mercedes-Benz has developed this diesel engine with an aluminium crankcase and cast-in grey iron cylinder liners. It tips the scales at only 41 kilograms and is therefore a prime example of lightweight construction. Aluminium is also used for the cylinder heads, cylinder head covers, pistons, coolant pump, sump and charge pressure distributor. Plastics are also used to save weight. Components in the fresh and charge air ducting systems, silencer and engine shrouding are of plastic.
A likewise newly developed valve control system reduces both friction and moving masses: the 24 intake and exhaust valves are controlled by an overhead camshaft for each cylinder bank, via roller-type rocker arms with hydraulic valve clearance compensation. The camshafts are driven by a tried-and-tested double-bush timing chain system into which the balancer shaft and the high-pressure pump for the fuel injection system are integrated.
Compact dimensions thanks to a new "one-box" design
Thanks to a newly developed "one-box" design, the V6 engine is among the most compact diesel power units in its displacement class worldwide. "One-box" design means that the engine forms a single, compact entity with its components and ancillary units. The complete air filter system is directly attached to the engine and therefore occupies no additional installation space. This makes the new V6 even more compact than the previous five-cylinder in-line unit.
In addition to lightweight construction, compact dimensions and low-friction valve gear, the new CDI six-cylinder would not be a Mercedes engine if it did not also meet the strict standards of the brand in terms of rigidity, vibration characteristics and long-term durability. Calculations and computer simulations provided the engineers in Stuttgart with valuable data and helped them achieve the demanding specifications. A look at the interior of the V6 engine:
- The forged crankshaft rotates in four bearings which have been enlarged by five millimetres compared with the in-line six-cylinder unit in the interests of vibration comfort. The radii of the crank pins have been rolled to achieve high strength. The flexural and torsional rigidity of the crankshaft is more than twice that of the preceding engines.
- The connecting rods are also of forged steel. Mercedes engineers have further optimised their weight by using a new alloy and making improvements to their geometry.
- Careful design of the combustion chamber geometry, which includes the precisely calculated recesses in the piston crowns, optimises the combustion process and helps to achieve a lasting reduction in untreated emissions.
- The free vibrations which are inherent to a V6 engine are compensated by a balancer shaft between the cylinder banks. This counter-rotates at the same speed as the crankshaft.
Heat exchangers for oil cooling, heating and exhaust gas recirculation
A separate roller chain is used to drive the oil pump. Via a large full-flow oil filter, the efficient and quiet external-gear pump delivers the oil to the oil-water heat exchanger located between the cylinder banks. The high 15-kW output of the heat exchanger ensures that even under extreme engine loads, the oil temperature does not rise above 130 degrees Celsius. The tunnel of the balancer shaft also serves as the main oil duct from which the oil flows to the main bearings, into the cylinder heads and to the piston-cooling spray units, which automatically open at a certain oil pressure and cool the pistons.
The mainstay of the water cooling system is a belt-driven pump on the crankcase. This is a double-helix pump which forces the coolant into the cylinder banks within the crankcase from the front, where it mainly flows to the exhaust side via special holes drilled in the cylinder head gasket. Cooling is thermostat-controlled on the cross-flow principle.
The flow of coolant for the oil-water heat exchanger comes from the crankcase on the right, while the exhaust gas recirculation (EGR) cooler and the heat exchanger for the heating system are supplied with coolant from the left cylinder head. The coolant circuit is therefore designed to ensure adequate heat dissipation under any load and engine speed conditions. Particularly high rates of flow are achieved at the valve lands, around the injector ducts in the cylinder heads, in the oil-water heat exchanger and in the exhaust gas recirculation cooler, enabling an efficient heat transfer to take place.
Turbocharger with variable nozzle turbine
The new V6 diesel engine is aspirated by a VNT turbocharger (Variable Nozzle Turbine). This technology already enables high levels of output and torque to be achieved at low engine speeds. Thanks to electric control, VNT turbochargers are able to vary the angle of their turbine blades rapidly and precisely to suit the operating status of the engine, and can therefore use the largest possible volume of exhaust gas to compress the intake air and build up charge pressure. At low engine speeds the turbine blades reduce the flow cross-section to increase the charge pressure, while the cross-section is enlarged at high engine speeds to reduce the speed of the turbocharger. More efficient cylinder charging and therefore higher torque are the results of variable, demand-related turbocharger control. Moreover, electric VNT technology allows a precise interaction with other units which are responsible for reducing untreated emissions and exhaust gas aftertreatment.
The turbocharger is combined with a downstream intercooler which reduces the temperature of the compressed, heated air by up to 95 degrees Celsius, allowing a larger volume of air to reach the combustion chambers. Behind the intercooler there is an electrically controlled flap which enables the V6 engine to be throttled back precisely when the exhaust gas recirculation is in operation. This electrically regulated control flap allows the volume and mix of the exhaust gases added to the combustion air to be very precisely metered. To optimise the volume of recirculated exhaust gas, it is abruptly cooled in a high-performance heat exchanger. Acting in conjunction with the hot-film air mass sensors integrated into the intake air ducts, which provide the engine control unit with precise information about the current volume of intake air, this significantly reduces nitrogen oxide emissions.
The combustion air then flows into the charge air distribution module, which supplies each cylinder in equal measure. The distribution module features an integral, electrically controlled intake port shut-off function with which the intake post cross-section for each cylinder can be variably reduced. This modifies the swirl of the combustion air, ensuring that the charge flow to the cylinders is adjusted for the best possible combustion and exhaust emissions under any load and engine speed conditions.
Piezo-ceramics for precisely metered injection within microseconds
The third generation of the well-proven common-rail direct injection system is entering series production at Mercedes-Benz with the new V6 diesel engine. This means that the injectors, high-pressure pump and electronic engine management system will operate even more efficiently, with a further reduction in fuel consumption, exhaust emissions and combustion noise.
Instead of the previous solenoid valves, the injectors are equipped with piezo-ceramics whose crystalline structure changes within milliseconds under an electric voltage. The engine developers used this effect, which was discovered in 1880 by the brothers Pierre and Jacques Curie, to lift the needle jet at the tip of the injector with a precision of mere thousandths of a millimetre and thereby achieve an extremely fine jet of fuel. Moreover, piezo injectors are considerably lighter and operate at twice the speed of conventional solenoid valves. With a response time of only 0.1 milliseconds, the fuel injection process can be even more precisely suited to the current load and engine speed situation, with favourable effects on emissions, fuel consumption and combustion noise. The number of fuel injections per power stroke is increased from three to five thanks to this piezo technology.
Mercedes engineers have also made improvements to other components of the common-rail system and the injection process:
- The hydraulically optimised injector nozzles have eight holes (previously seven), which ensures even finer distribution of the fuel within the combustion chamber and more efficient mixture formation.
- The inlet-metered high-pressure pump operates with a maximum injection pressure of 1600 bar.
- The pilot injection process developed by Mercedes-Benz, which ensures a smoother combustion process and thereby audibly reduces the operating noise of the engine, takes place twice in succession in the new V6 engine. Small pilot quantities of fuel are injected within less than a millisecond and preheat the combustion chambers even more efficiently.
- To burn off the soot particles in the particulate filter, there is a double post-injection of fuel when required.
Emission control with two catalytic converters and a particulate filter
Two oxidising catalytic converters clean the exhaust gases emitted by the new Mercedes diesel engine. One acts as pre-catalytic converter, and is ready for action very soon after a cold start thanks to its position close to the engine. This unit is accompanied by a downstream main catalytic converter. The purpose of the oxidation-type catalytic converters is to convert carbon monoxide and unburned hydrocarbons by combining them with oxygen to form chemical compounds (oxidisation).
This efficient exhaust gas aftertreatment combined with the complex in-engine measures already enables the V6 diesel engine to meet the stringent EU4 exhaust limits.
To lower exhaust emissions even further, Mercedes-Benz combines the new six-cylinder powerplant with a maintenance-free particulate filter system (standard in Germany), leading to a further significant cut in particulate emissions. The particulate filter regenerates itself without the use of additives and remains effective over a very high operating mileage.
ML 350 with a new 200 kW/272 hp six-cylinder engine
Output, torque, fuel consumption, comfort and exhaust emissions – these were also task areas of equal importance when developing the new V6 petrol engine. This up-to-date six-cylinder unit makes its mark in each of these disciplines. It offers technical innovations which do not just represent stand-alone solutions, but rather have a positive impact across a number of areas.
The Mercedes engineers had already created important conditions for an exemplary performance curve with four-valve technology and four overhead camshafts, but this was not yet enough for them. In addition they developed a system by which the interaction of the 24 valves can be controlled as required – depending on the engine load – while ensuring an extremely rapid gas cycle in the cylinders: continuously variable camshaft adjustment. This means that the angles of both the intake and exhaust camshafts can be continuously varied by 40 degrees, ensuring that the valves open or close at the best possible moment in any driving situation.
Under low engine loads the engineers have used this technology to allow the exhaust gases to flow directly from the combustion chamber and back to the intake duct: during the process the camshafts are adjusted so that the exhaust valves remain open for a short time while the intake valves are opening. During this split second, some of the exhaust gases are able to flow from the exhaust duct to the intake duct. The vacuum pressure in the intake manifold assists this process.
This valve overlap when venting the exhaust gases and taking in the fresh mixture makes an efficient internal exhaust gas recirculation possible. This reduces the energy losses during the charge cycle in the cylinders, leading to a significantly lower fuel consumption.
Under higher engine loads the camshaft adjustment feature is also used to optimise the valve overlap in line with the engine speed so that the combustion chambers are efficiently supplied with fresh mixture – which makes for a high power and torque output.
The V6 developers devoted a great deal of attention to anything that would contribute to optimal aspiration. Sophisticated computer programmes were used to calculate airflows, e.g. helping to optimise the flow of air from the twin-chamber air filter. This is where the ducts interface with the hot-film air mass sensor (HFM). The housing of this unit is oval in shape for optimal flow characteristics and accommodates an electrically heated sensor element which measures the flow of intake air, providing the engine management system with important basic information for the composition of the combustion mixture.
An intake module produced in well-proven magnesium technology enables the air intake to be varied according to the engine load and rev speed. The length of the intake pipes leading to the cylinders is varied by means of flaps. At high engine speeds – from approx. 3500 rpm – the flaps are open and the air takes the shortest distance to reach the combustion chambers, producing a high engine output. At low engine speeds the flaps are closed, increasing the length of the intake duct. This creates pressure waves which assist the intake process and fundamentally improve the torque generated in the lower engine speed range. No less than 305 Newton metres are already available from 1500 rpm, which corresponds to approx. 87 percent of the maximum torque.
Tumble flaps in the intake ducts
Electro-pneumatically driven flaps at the end of each intake duct are the special feature of the intake module in the Mercedes six-cylinder engine. These make a significant contribution to fuel economy. Mercedes engineers refer to these as tumble flaps, which in some measure indicates their purpose: they literally cause the fuel/air mix to tumble, increasing the turbulence of the airflow and causing it to enter the combustion chambers at higher speed, with a more uniform distribution. The result is better, more complete combustion.
At partial throttle, the tumble flaps pivot upwards, optimising the airflow and increasing the speed of combustion – an advantage that makes itself particularly noticeable in terms of fuel economy where the mixture is lean as a result of exhaust gas recirculation. Under higher engine loads the tumble flaps are not required, and can be completely recessed into the intake manifold so as not to impede the intake process. Situation-related control of the tumble flaps is based on stored characteristic maps.
By virtue of the tumble flaps in the intake ducts, the fuel consumption of the V6 engine can be reduced by up to 0.2 litres per 100 kilometres depending on engine speed – while improving smoothness at the same time.
Aluminium crankcase and cylinder head
The cylinder head and crankcase of the new V6 engine are of aluminium. The pistons, connecting rods and cylinder liners are produced according to the latest design principles, which not only contribute to weight reduction but also have a positive effect on engine responsiveness and smooth running. For the lower the moving masses in the crankcase, the lower the vibrations and the more responsive the engine becomes to movements of the accelerator pedal:
- The pistons are of iron-coated aluminium. Taking into account the valve angle (28.5 degrees), the piston crowns are designed to ensure a favourable combustion chamber shape.
- Mercedes engineers have been able to reduce the weight of the forged steel connecting rods by approx. 20 percent compared to other V6 engines, thereby making a significant contribution to the extreme smoothness of the new six-cylinder power unit.
- The cylinder liners benefit from low-friction surfaces featuring aluminium-silicon technology which have also proven their worth in other Mercedes-Benz car engines. Other advantages include minimal distortion, exemplary thermal flows and low weight. The weight saving compared to conventional cast-iron liners is approx. 500 grams per cylinder.
- The forged crankshaft is equipped with four counterweights. Four wide crankshaft bearings attached to the crankcase by transverse reinforcing struts also contribute to reduced vibrations.
- A balancer shaft between the two banks of cylinders compensates the free vibrations inherent to a V6 engine and ensures exemplary smoothness. It counter-rotates at the same speed as the crankshaft.
Emissions control using in-engine measures and catalytic converters
The emission control system follows a two-stage concept: it is based both on sophisticated engine-specific measures for a reduction in untreated emissions and on highly effective emission control using two catalytic converters located close to the engine with a volume of 1.3 litres each. Each of these is equipped with two oxygen sensors – a control sensor and a diagnostic sensor – with linear control. This means that the oxygen sensors are already active immediately after a cold start, supplying information about the exhaust gas constituents for the electronic engine management system to process when controlling the warm-up phase.
The engine-specific measures include e.g. variable camshaft adjustment, which makes efficient internal exhaust gas recirculation possible under partial load. In the same way the adjustable tumble flaps in the intake ducts, which improve the combustion process, make an important contribution to minimising the untreated engine emissions. A secondary air injection system is also used. This has an afterburning action on the exhaust gases, increasing the temperature in the exhaust ducts and enabling the catalytic converter to start converting the pollutants at an earlier stage. During this afterburning process the carbon monoxide and hydrocarbon content in the untreated exhaust gases is also reduced.
Eight-cylinder powerplant with 10 kW/14 hp more output
The V8 engine of the new ML 500 generates 225 kW/306 hp from a displacement of 4966 cubic centimetres - 10 kW/14 hp more than before. An electronically controlled intake module increases the torque available at low engine speeds and ensures that whether in town or on country roads, the engine is always able to respond immediately to the driver’s power requirements. More than 400 Newton metres are already available from 2000 rpm, corresponding to almost 90 percent of the maximum torque of 460 Newton metres which the eight-cylinder unit places on tap at 2700 rpm and maintains up to 4750 rpm.
Seven-speed automatic with DIRECT SELECT as standard
On board the M-Class, the powerful six and eight-cylinder engines and the seven-speed automatic transmission 7G-TRONIC form a strong team. With a number of special technical features, this transmission fully exploits the characteristics of the engines and therefore makes a major contribution to brisk acceleration, rapid intermediate sprints, a favourable fuel consumption and a high level of gearshift comfort.
The 7G-TRONIC transmission has a further special feature on board the new Mercedes Off-Roader: DIRECT SELECT. This means that the conventional automatic selector lever in the centre console is replaced by a selector stalk on the steering column, which the driver nudges to select the transmission settings "P", "N", "R" and "D". Operating commands are transmitted electronically by wire, which is why the system is referred to as "shift-by-wire". For drivers with sporty inclinations who wish to operate the transmission manually in certain driving situations, the new M-Class is equipped with steering-wheel gearshift buttons as standard.
When the new M-Class is equipped with the Off-Road Pro engineering package, 7G TRONIC features a manual "M" mode which likewise enables the gears to be selected using steering-wheel buttons.
The special qualities of the world’s first seven-speed automatic transmission for passenger cars are the product of a number of design features. The most important is the increase in the number of forward gears from the previous five to seven. This allows a wider spread of ratios, as well as further reducing the differences in engine speed between the individual gears achieved by a five-speed transmission. As a result, the driver can rely on having the optimum ratio at his or her disposal for virtually any driving situation. In addition, the electronic control unit has even more scope with which to optimise the shift processes to achieve lower fuel consumption and greater comfort. For example, at 100 km/h the engine speed will be on average – depending on the driving situation - around twelve percent lower than with a five-speed automatic. This impressive engine speed adjustment system opens the door to lower noise, as well as improved fuel economy.
Mercedes engineers have achieved further important advances where shift control is concerned: if the driver needs to accelerate quickly and therefore change down rapidly through several gears - i.e. kick-down - 7G-TRONIC avoids having to move through the gears in strict order. Instead, the transmission uses its direct downshift capability, shifting down by as many as four gears – as the situation requires – rather than just one at a time. Shift times have been reduced significantly below the levels of the previous five-speed automatic transmission.
The seven-speed automatic transmission also features a torque converter lockup clutch. This is located in the hydrodynamic torque converter and largely eliminates slip between the pump wheel and the turbine wheel in many It manages this by establishing – where possible – a virtually rigid connection between the engine and transmission shafts, thus preventing power losses. In contrast to conventional automatic transmissions, where the converter can only be locked up in higher gears, the lock-up clutch in the seven-speed automatic transmission by Mercedes -Benz is already active in first gear. In addition, in the interests of comfort, the torque converter lock-up clutch features slip control, which allows it to run extremely smoothly. This is another way in which Mercedes engineers have achieved optimal shift quality.
Whether taking bends at speed, on long motorway journeys or on difficult terrain, the suspension of the new M-Class is equal to any challenge. Mercedes engineers have newly developed the axles, steering, brakes and suspension, and adapted them to match the varied operating requirements of the Off-Roader. The result is a technical masterpiece which meets the highest demands in terms of both handling dynamics and ride comfort. Individual customer wishes can now also be met with respect to suspension technology: available options include an AIRMATIC package with the Adaptive Damping System (ADS) and the Off-Road Pro engineering package with differential locks, low-range ratios, an underride guard and AIRMATIC with extended functions for even greater ground clearance.
The front wheels are located by a newly developed double-wishbone suspension whose upper wishbone is located in a high position. In conjunction with the robust subframe, engine, transmission, steering and axle, this suspension principle has enabled Mercedes engineers to achieve an ideal compromise between a high load-bearing capacity, good ride comfort and exemplary handling characteristics. The upper wishbone is of forged aluminium, while the lower wishbone and steering knuckle are of nodular cast iron. Four rubber bearings isolate the subframe from the vehicle body and make a major contribution to the vibration comfort of the new M-Class.
This front suspension with its high control arms is equipped with spring struts whose longer spring travel and more effective rubber bearings provide better ride comfort than the preceding series. The spring struts contain cylindrical coil springs, single-tube gas-pressure shock absorbers and large head bearings. The torsion bar stabiliser is attached to the spring strut by a linkage.
Speed-sensitive power steering as standard
The steering gear of the new M-Class is positioned in front of the wheel centre, and therefore where it can support the slight but easily controlled understeer of the Off-Roader on bends. The servo-assisted rack-and-pinion steering has a variable ratio which operates a little more directly in the central position than in the outer positions. Additional comfort is provided by the speed-sensitive power steering, which continuously reduces the steering effort below 100 km/h as a function of vehicle speed. This is made possible by an electronically controlled valve: the lower the speed, the higher the servo effect. Accordingly only half the steering effort is required when parking the vehicle than when driving on the motorway, where the speed-sensitive power steering provides good road contact. This comfort feature is standard equipment in the new Mercedes Off-Roader.
Mercedes-Benz has developed a four-spoke steering wheel with a diameter of 385 millimetres for the M-Class whose die-cast magnesium structure is designed to deform specifically during a frontal collision, thereby reducing the risk of injury to the driver. The steering wheel is an important part of the operating and display concept with its conveniently placed, illuminated keys, as it allows various functions such as the radio, car telephone or the central display in the instrument cluster to be operated by slight thumb pressure.
The newly developed steering column, which is able to collapse telescopically by up to 100 millimetres during a frontal collision, can be individually adjusted for height and reach. Electric adjustment is also available as an option.
Newly developed four-link technology at the rear axle
Like the front axle, the rear axle is mounted on a subframe which is effectively isolated from the bodyshell by two rubber bearings and two hydro-mounts. Mercedes engineers have developed a four-link suspension design which basically consists of the following elements:
- Lower wishbone: This axle component is made from nodular cast iron.
- Upper steering arm: This is an assembly of sheet steel camber arms and forged steel rods.
- Track rods: These are located behind the wheel centre and are of welded tubular construction.
The rear axle coil springs and single-tube shock absorbers are positioned in line. A torsion bar stabiliser is also used.
AIRMATIC air suspension in on-road and off-road configurations
The AIRMATIC air suspension system (optional) developed by Mercedes-Benz proves its versatility in the new M-Class. It not only makes a significant improvement to ride comfort, but also offers additional functions for off-road driving.
Mercedes customers are offered a choice: the AIRMATIC package provides an air suspension configured for on-road operation which automatically lowers the suspension by 15 millimetres at higher speeds. For off-road driving this system enables the ground clearance to be increased by 80 millimetres at the touch of a button. The second AIRMATIC variant, which is part of the Off-Road Pro engineering package, enables the vehicle level to be raised in three stages by operating a button: by 30, 80 and 110 millimetres. This gives the new M-Class its maximum ground clearance of 291 millimetres.
It is possible to raise or lower the suspension both when idling or on the move. If the M-Class is moving, the system operates on a speed-dependent basis and automatically lowers the suspension by 15 millimetres at both axles when 140 km/h is reached, in order to reduce the wind resistance and improve handling stability. When the speed falls below 40 km/h the suspension is raised to its normal level again. Other features of the air suspension system include an automatic all-round level control function, which ensures that the suspension travel remains constant even when the vehicle is heavily laden.
Adaptive shock absorber control according to the driving situation
In both variants AIRMATIC works as standard together with the Adaptive Damping System (ADS), which controls the shock absorber response in line with requirements while taking the road surface, driving style and load into consideration. Selectable solenoid valves in the shock absorbers enable the rebound and compression damping to be modified according to the situation, which considerably reduces body movements. The so-called skyhook algorithm controls the damping forces at each wheel in such a way that the wheel-induced forces acting on the vehicle body are reduced. Thanks to this precise control for each individual wheel, the two front wheels can e.g. be damped more heavily than the rear wheels to reduce the tendency of the body to dive when braking. Depending on the control command, the valves are able to select one of four characteristic curves within an extremely short response time of less than 0.05 seconds:
- Stage 1: Comfortable suspension action with small body movements and low acceleration values owing to soft compression and rebound settings.
- Stage 2: Skyhook mode – soft rebound setting and a hard compression setting.
- Stage 3: Skyhook mode – soft compression setting and hard rebound setting.
- Stage 4: Hard rebound and compression setting to reduce wheel load fluctuations when cornering at speed.
When body movements are small the new M-Class operates in ADS stage 1. If body acceleration values exceed a certain level, the system changes over to the skyhook algorithm and uses its rapid-response solenoid valves to continuously switch between the second and third damping stage to compensate the rolling and pitching movements of the vehicle body. The current driving situation is identified by means of a steering angle sensor, three body-mounted acceleration sensors, the speedometer signal giving the road speed, data from the Electronic Stability Program (ESP®) and the signal from the brake pedal switch. On the basis of this information the electronic control unit calculates the most efficient damping forces and selects the relevant characteristic curves for the shock absorbers.
n addition the driver is able to influence the changeover thresholds between the four ADS stages, as well as the spring rate, by pressing a button in the centre console. There is a choice of three modes: "Auto", "Sport" and "Comfort".
The variable ADS gas-pressure shock absorbers and air spring are integrated into a spring strut at the front axle of the new M-Class. At the rear axle the ADS shock absorber is located behind the air spring. Torsion bar stabilisers are also used at both the front and rear.
Larger front and rear brake discs
The new M-Class features generously dimensioned, internally ventilated front brake discs. In the six-cylinder models these have a diameter of 330 millimetres -27 millimetres more than before. The top-of-the-line ML 500 is equipped with even larger brake discs (350 millimetres). At the rear axle Mercedes-Benz uses solid disc brakes with a diameter of 330 millimetres - 45 millimetres more than in the previous M-Class.
Sports package with 19-inch light-alloy wheels
Wide-base tyres and 17 or 18-inch light-alloy wheels underline the sporty, dynamic appearance of the new M-Class. The six-cylinder models are fitted with 17-inch light-alloy wheels in a seven-spoke design and size 235/65 R 17 wide-base tyres as standard. The ML 500 has 18-inch light-alloy wheels in the five-spoke "impeller" design and size 255/55 R 18 tyres. A different 18-inch wheel in a five-twin-spoke design with 255/55 R 18 tyres is optionally available for all the model variants.
The wheels Mercedes-Benz offers in conjunction with the sports package are even larger and more attractive: these 19-inch light-alloy wheels in a five-spoke design are also optionally available in a chrome-plated version which creates an additional visual highlight.
ESP® with tyre pressure warning function
ABS, ASR, ESP®, Brake Assist – these well-proven dynamic safety systems developed by Mercedes-Benz are standard equipment in the new M-Class.
The Electronic Stability Program not only keeps the Off-Roader safely on course, but also monitors the tyre pressures in its latest version: the system continuously compares the wheel rotation speeds, which mainly depend on the vehicle speed, vehicle load and tyre pressures. It is therefore able to detect any significant deviations. In addition the control unit automatically monitors other dynamic parameters such as the lateral acceleration, yaw rate and wheel torque in order to diagnose any pressure loss in a tyre reliably, though this system does not measure the actual air pressure in each tyre. If a loss of pressure is detected in a tyre, a warning appears in the cockpit’s central display: "Tyre pressure, check tyres." This warning function for tyre pressure loss based on ESP® technology is standard equipment in the new M-Class.
The assignment to develop a modern off-roader with a future-oriented concept was taken very seriously by the bodyshell developers at the Mercedes-Benz Technology Center. Nothing remained sacred, and all the body parts and components were re-examined. Safety, lightweight construction, operating reliability, handling stability, aerodynamics and long-term durability were just some of the many aspects which had to be considered and reconciled, even though some requirements seem contradictory at first sight. However, resolving apparently conflicting aims made the M-Class project all the more interesting for the engineers in Sindelfingen, and encouraged them to redouble their efforts.
A self-supporting, rigid bodyshell creates the conditions for safe handling and a high level of ride comfort, and forms the basis for even better occupant protection and modern lightweight construction methods. This is where the new M-Class differs from the preceding series with its structural frame. In order to cope with the high loads occurring in off-road operations, the highly stressed areas between the vehicle suspension and the bodyshell were redesigned and – above all - redimensioned.
One indication of the bodyshell’s qualities is the considerably higher torsional rigidity, which is now 2.18 millimetres per metre (static) and therefore significantly betters that of the preceding series. Accordingly the bodyshell makes an important contribution to the noticeably improved vibration comfort and excellent handling stability of the new M-Class. This outstanding torsional rigidity is in part due to a continuous frame structure in the roof area, which is used to attach the tailgate and also forms a robust connection between the side walls, floor and rear roof frame. This "D-ring", as it is known, literally has a firm grip on the entire bodyshell and increases its torsional rigidity.
The body of the M-Class has been generally redimensioned: the new Off-Roader is 150 millimetres longer, 71 millimetres wider and five millimetres lower than its predecessor. The increased length is mainly due to the 95-millimetre longer wheelbase and the 56-millimetre longer rear overhang.
Two thirds of all body panels made from high-strength steel alloys
The latest production processes and the intelligent use of materials have made progress possible with respect to lightweight construction, tolerances and ease of repair. While conventional steel continues to predominate in the material mix for the new M-Class, Mercedes-Benz has made a five-fold increase in the proportion of high-strength alloys, which offer maximum strength for the minimum panel thickness and weight. In terms of total body weight, 62 percent of all the body panels are now of high-strength steel alloys. Some of these, e.g. those of dual-phase steel, are even in the "very high strength" category. The special, two-phase microstructure of this alloy is capable of withstanding very high loads and therefore contributes significantly to the exemplary stability of the front end and passenger cell.
Numerous sheet metal components in the bodyshell of the new M-Class are assembled according to the "stress-relieved joining" principle, which allows a high level of precision. For example, the flanges at the edges of steel panels are designed in such a way that any tolerances are already compensated when positioning the sheets together, which permits body components to be welded together without significant stresses. This joining technique and the precise design of the body components also makes a major contribution to corrosion protection, as it substantially dispenses with additional brazed connections and MAG-welding seams which are generally seen as areas particularly vulnerable to corrosion.
Fully galvanised body panels and nano-technology paint with improved scratch resistance
As in all the latest Mercedes passenger cars, the long-term corrosion protection of the new M-Class is based on fully galvanised sheet metal which is also organically coated on both sides, depending on the area of application. This coating also contains rust-inhibiting zinc pigments. Highly stressed structural areas of the bodyshell are also protected by cavity preservation, and the welding seams are carefully sealed. The six-section plastic underbody cladding, which gives protection against stones, water and soiling, makes it possible to dispense with a conventional PVC underbody coating. The wheel arch liners of three-millimetre thick plastic likewise give protection against stone impact.
Mercedes-Benz also makes a major contribution to exemplary long-term quality and value retention with an innovative, more scratch-resistant clear paint coat based on nano-technology. This innovative paint system, which had its world debut with Mercedes-Benz, is standard equipment for the new M-Class; it is used for both metallic and non-metallic paint finishes.
Thanks to remarkable advances in the science of nano-technology it has been possible to integrate ceramic particles measuring less than one millionth of a millimetre into the molecular structure of the paint binder. These nano-particles achieve a three-fold increase in the scratch-resistance of the paint finish, ensuring a visibly improved and lasting sheen.
Front-end structure with crash boxes and robust structural members
Dispensing with the previous structural frame has made it possible to design the front-end structure of the new M-Class to passenger car standards. This particularly benefits occupant safety during a frontal collision.
Two straight side members of high-strength steel reinforced with two interior sheet steel liners, a front element and two outside members above the wheel arches are the most important energy-absorbing features of the front end. Energy is absorbed in stages, depending on impact severity. The front end is equipped with two crash boxes of high-strength steel which absorb the impact energy in the event of a frontal collision at low speeds (up to 15 km/h).
The crash boxes are bolted to the side members and can therefore be inexpensively replaced without welding in the event of damage. All the other components in the front end are also bolted together for ease of repair.
Only at higher impact speeds (above 15 km/h) are the robust side members in the front end activated to form a deformation zone. If the body structure is subjected to one-sided loads, i.e. during an offset frontal impact, an aluminium section and other transverse connections in the front end ensure that the impact forces are also dissipated to the unaffected side of the vehicle. During an offset crash the second level of side members above the wheel arches also serves to dissipate impact energy.
The high-strength steel subframe which carries the front axle, steering gear, engine and transmission is also specifically deformed during an impact, and thereby makes a major contribution to energy absorption. The front wheels are also integrated into the safety concept; during a collision they are supported by the robust side walls and direct impact forces away from the passenger cell.
Effective all-round occupant protection
While the front-end structure is designed and constructed to deform and absorb energy during an accident, the passenger cell of the new M-Class forms a protective area with a high deformation resistance. The floor assembly, roof pillars, side members and side walls are the most important components of this rigid safety zone:
- The main floor consists of three assemblies. The centre section - the transmission tunnel – has a higher steel thickness and therefore acts as the backbone of the floor structure. The areas on both sides of the tunnel are reinforced with cross-members which provide a solid mounting base for the seats and ensure a high level of lateral stability, which particularly benefits occupant protection in the event of a lateral collision. In addition a diagonal member extending from the firewall to the B-pillars strengthens the floor assembly.
- The external side panels and multi-piece interior side wall components form the multi-layered cross-sections of the roof pillars, roof frame and side members.
- The reinforced outer shells of the side walls are one-piece units; the inner shells consist of several steel sheets which are particularly robust at the nodal points where the roof pillars join the roof frame and the side members.
In addition to aero-acoustics, sound-absorbing foam components contribute to the excellent noise comfort on board the new M-Class. These are concealed at various points of the bodyshell – 34 such foam elements are integrated into the two side walls alone.
Easy-repair rear-end design
The rear side members of the new M-Class are designed as continuous, closed box sections with gradually reducing material thickness. These make a major contribution to occupant safety during a rear-end collision. The fuel tank is located in an impact-protected position in front of the rear axle.
In the interests of repair-friendly design the rear end also features steel crash boxes and a deformable aluminium cross-member. These absorb impact forces during minor collisions (up to a maximum of 15 km/h) so that the main body structure remains undamaged. Bolted connections allow damaged crash boxes and the cross-member to be replaced inexpensively.
The world’s first off-roader with PRE-SAFE® anticipatory occupant protection
With adaptive front airbags and belt force limiters, belt tensioners, sidebags and windowbags, as well as newly developed crash-responsive head restraints (optional), the M-Class is well-prepared for all types of accident where occupant protection is concerned. But the developers of the Off-Roader were not satisfied to leave it at that. They are offering customers an even more intelligent system which can already become active in the few seconds preceding an impending accident: PRE-SAFE®.
With this anticipatory occupant protection system, which Mercedes-Benz first realised in the S-Class in 2002, the M-Class underlines its role as a trendsetter and example. No other off-roader offers this unique, trailblazing technology.
PRE-SAFE® creates the link between active and passive safety. It is networked with Brake Assist and the Electronic Stability Program (ESP?) and recognises critical handling situations which might lead to an accident. PRE-SAFE® intervenes in such dangerous situations within milliseconds, preparing both the occupants and the vehicle for the possible collision:
- The seat belts of the driver and front passenger are pulled taut as a precaution.
- If the electrically adjustable front passenger seat with memory function (optional) is adjusted to an unfavourable fore-aft setting or cushion/backrest angle, it is moved to a better position.
- The sunroof is closed if there is a risk of the vehicle rolling over.
Thanks to these precautionary PRE-SAFE measures the vehicle occupants are in a better seating position even before the accident occurs, enabling the seat belts and airbags to work more efficiently. If the accident is avoided, the preventive tensioning of the seat belt is automatically relaxed and the passengers are able to return the seat and sunroof to their previous positions.
Adaptive airbags and belt force limiters
The restraint systems also respond according to need on the basis of an efficient sensor system. In addition to the central crash sensor in the centre console, Mercedes -Benz employs up-front sensors for this purpose; these are located on the radiator cross-member in the front end structure, and their remote positioning in the front end of the body enables them to detect the severity of a collision even earlier and with greater accuracy. This makes it possible to shorten the time that elapses between the moment of impact and the deployment of the airbags and belt tensioners even further. In other words, the seat belts are tensioned at a very early stage so that the occupants are optimally linked to the passenger cell and take part in the vehicle deceleration process during an impact.
The electronic control unit also uses the information from the up-front sensors to deploy the driver and front passenger airbags sooner and as the situation demands. This takes place in two stages, depending on the severity of the impact: during a minor frontal impact the electronic control unit only ignites one stage of the two-stage airbag gas generators, and the airbag inflates more gently. Should the control unit detect a severe frontal collision, however, it deploys the second stage of the gas generator after a slight delay. As a result, the airbags inflate at a higher pressure to provide the occupants with the level of protection required in a collision of this severity. By virtue of a newly developed, energy-absorbent and telescopic steering column which compresses by up to 100 millimetres during a collision, the driver is given far more space for forward motion.
The belt force limiters are also adaptive, i.e. they operate according to the accident situation: if the sensors send information that a frontal collision is severe, the seat belts are tensioned and reach their maximum retaining power. Briefly afterwards the force limiters switch to a lower level of force, which slackens the belts slightly and allows the front occupants to sink more deeply into the airbags. This reduces the loads acting on the chest area.
Newly developed crash-responsive NECK-PRO head restraints
Mercedes-Benz has perfected occupant protection during a rear-end collision with newly developed, crash-responsive NECK-PRO head restraints for the driver and front passenger (optional), which celebrate their premiere in the M-Class. These are likewise linked to the control unit: if the sensor system detects a rear-end collision with a defined impact severity, it releases pre-tensioned springs inside the head restraints which immediately cause these to move forward by about 40 millimetres and upwards by 30 millimetres. This means that the heads of the front occupants are supported at an early stage, reducing the risk of whiplash injuries. After NECK-PRO activation the head restraints can be unlocked and returned to their original position using a tool supplied with the car.
Sidebags and windowbags as standard
With standard-fitted sidebags for the driver and front passenger, as well as windowbags, the restraint system of the new M-Class provides two further, highly-effective systems whose protective effect is complementary: while the sidebags primarily reduce the loads acting on the chest area, the windowbags provide head protection over a wide area for both front and rear occupants. During a lateral impact the windowbag inflates and extends from the front to the rear roof pillar like a large curtain. Accordingly it also gives protection against objects which might penetrate into the vehicle interior during a crash. Sidebags are also optionally available for the rear.
A special sensor system is responsible for deployment of the sidebags within milliseconds: in addition to the central sensor in the interior, satellite sensors located in the side members provide information about the severity of a lateral collision.
The sophisticated crash sensor system in the new M-Class is rounded off by a roll-over sensor which activates the belt tensioners and windowbags during certain types of lateral impact. A special, laminated coating on the weave ensures that the windowbags remain inflated for some time after a roll-over.