2007 Mercedes CL-Class

Body

The bodyshell of the new CL-Class is another excellent example of how very different aspects can be successfully integrated. As a robust backbone it stabilises the running gear, ensures precise handling and prevents uncomfortable vibrations. It also meets the most stringent Mercedes safety standards with its intelligent lightweight construction, has exemplary aerodynamic properties and has made audible progress in the field of vehicle acoustics.

These results are based on the careful selection of materials on the well-tried Mercedes principle of "the right material in the right place". The material mix consists of steel, aluminium and plastics, with steel continuing to play the major role. Here too, a technological change is taking place: conventional deep-drawn steels are becoming less important, and only account for around 26 percent in the new Mercedes-Benz CL-Class. Instead the specialists in Sindelfingen have opted for high or higher-strength steel alloys, which achieve maximum strength with minimum weight. Accordingly the proportion of these steel types has increased from eleven to around 44 percent compared to the preceding model.

In addition, ultra high-strength, high-tech steel alloys are used in body areas which are important for occupant protection. These are already formed in a warm state, thereby achieving an extremely high tensile strength which exceeds that of conventional steels by a factor of three. This means that half the bodyshell of the new CL-Class consists of high-tech steel alloys.

Mercedes-Benz uses the lightweight material aluminium where it has most advantages compared to steel. In the new CL-Class these areas are:

• Bonnet
• Front wings
• Exterior door panels
• Front-end module member
• Rear-end module member
• Bulkhead behind the rear seat backrest
• Rear end centre assembly

The boot lid and spare wheel recess are likewise of lightweight material, namely plastic.

High-tech adhesive in addition to welded connections

In addition to these high-tech materials, a combination of modern joining techniques contributes to the exemplary torsional and flexural rigidity of the bodyshell. A new, high-strength structural adhesive supplements conventional processes such as spot/laser welding and low-stress clinching. The adhesive creates a firm bond between the steel flanges, significantly increasing the load resistance and transfer of forces in safety-related areas. The total length of high-strength bonded seams in the new CL-Class has more than doubled versus the preceding series.

The precise dimensions of the body components, low-stress joining techniques and the latest spot or laser welding processes make additional brazed connections and MAG welding seams between the steel panels almost completely unnecessary – a major contribution to the durability of the bodyshell.

Easily repaired modules at the front and rear ends

The engineers in Sindelfingen adopted the well-proven modular concept for the front and rear ends of the new CL-Class, though with certain detailed design improvements. The flexible cross-members of these modules are now of high-strength extruded aluminium sections. These are connected to the longitudinal members via steel crash boxes, and designed so that the impact energy of a low-speed collision is first absorbed by the aluminium sections and crash boxes. This means that the downstream body structure remains undamaged. During an offset frontal collision, the robust cross-members also have the task of transferring impact energy to the unaffected side of the body structure.

The front and rear-end modules are bolted to the bodyshell, and can be replaced without troublesome welding work if repairs are required. The individual components within the modules are also connected with bolts.

Hybrid construction of two lightweight materials for the doors

The doors are of frameless, lightweight aluminium/magnesium construction: the interior parts are of magnesium, while the outer skin is of aluminium alloy. Side impact protection is provided by internal reinforcing sections of high-tensile aluminium. Mercedes engineers also devoted particular attention to the door hinges, for which they developed special, high-strength mounting plates. This creates a robust, integrated structure which provides effective protection to the occupants in the event of a lateral collision.

In addition to a high level of safety, the doors of the new CL-Class also have functions which make access and egress easier. A newly developed hydraulic system ensures that the open doors remain in position above an opening angle of 15 degrees – even on gradients or in strong wind. An electric servo mechanism pulls both doors (and the boot lid) closed.

Long-term protection: fully galvanised bodyshell and paint with nano-particles

Mercedes-Benz has developed an effective package of measures for long-term anti-corrosion protection. This is based on fully galvanised body panels, some of which have an additional organic coating on both sides depending on their location, e.g. on the doors or on the front, side and rear longitudinal members. This coating also contains rust-inhibiting zinc pigments. Mercedes-Benz also protects the most vulnerable structural areas of the bodywork with a cavity-fill preserving agent, for example on the front side members, the upper side member plane, the side members and the rear wheel arches.

The Mercedes-Benz experts also weather-seal the welding seams in order to prevent the onset of corrosion. This seam sealing benefits not only the bonnet, doors, tailgate, rear wheel arches and fuel filler flap, but also a large proportion of the welded joins in the floor structure of the new CL-Class. Using plastic for a large area of the underbody panelling has allowed Mercedes engineers to dispense with conventional PVC underseal. This underbody panelling protects the body from stone chippings, water and soiling.

In keeping with all Mercedes passenger cars, the new CL-Class is also protected by the 30-year MobiloLife warranty.

Mercedes-Benz also makes a major contribution to exemplary long-term quality and value retention with a scratch-resistant clearcoat based on nano-technology. This innovative paint system, which celebrated its world debut at Mercedes-Benz, is a standard feature of the new CL-Class and is used for both metallic and non-metallic finishes.

Thanks to advances in the field of nano-technology, it was possible to integrate the tiny ceramic particles measuring less than one millionth of a millimetre into the molecular structure of the paint binder. These particles effect a three-fold improvement in the scratch-resistance of the paint finish and ensure a visibly brighter, long-lasting sheen.

Aerodynamics: exemplary wind resistance and wind noise

The aerodynamics engineers at Mercedes-Benz have achieved another triumph where the new CL-Class is concerned. Despite larger wheel arches and greater demands in terms of engine cooling and interior climate control, the luxury Coupé has an even better coefficient of drag than its predecessor, with a Cd value of 0.27. This means that the new Mercedes Coupé also sets the standard for its class where aerodynamic efficiency is concerned.

The fact that the good aerodynamics of the CL-Class not only produce an exemplary Cd value, but also have a positive effect on handling safety, is demonstrated by the favourable values for front and rear axle lift. These are up to eleven percent lower than those of the preceding model, and are reliable indicators of high braking stability, good roadholding and a low susceptibility to side winds.

Comfort as an audible experience

The good aerodynamics of the CL-Class are also noticeable in acoustic terms, for if the airstream passes across the outer skin with minimal turbulence in the interests of low drag, this also leads to less noise. As early as the conceptual phase, Mercedes engineers took pains to ensure that the bodyshell was optimally streamlined so that wind noise was reduced.

It was with this in mind that they designed the airflow-efficient A-pillars, developed a more rigid bodyshell with reinforced outer surfaces and achieved a new sealing concept for the doors, which is acoustically even more efficient than in the preceding model. This exemplary noise insulation is also helped by the side windows, which have a thickness of six millimetres in the new CL-Class.

Many other components were also developed with a view to aero-acoustic efficiency: for example the windscreen wipers, which are positioned very low down, out of the airstream, when parked. A narrow stem between the exterior mirror housings and the doors also prevents wind noise, and a specially designed rubber seal between the rear window and the boot lid also makes for aero-acoustic efficiency. The tilting/sliding sunroof features serrated wind deflectors whose ridges create designed-in longitudinal air turbulence, thereby reducing thrumming noises when the roof is open.

Noise analyses with a three-metre parabolic mirror

To carry out their aero-acoustic measurements, Mercedes engineers developed a new procedure involving a three-metre parabolic mirror fitted with numerous microphones, which acts as a sound reflector. From a distance of five metres, the microphones at the focal point of the mirror record the noises caused by the airstream as it passes around the vehicle body.

While numerous individual measurements were formerly necessary for such analytical procedures, the new parabolic mirror process requires only a single measurement to examine complete areas of the vehicle body, e.g. the A-pillar, exterior mirror, side window and roof.

A video camera makes the area under examination visible on the computer screen. At the same time the system superimposes the wind noises onto the video image as different-coloured areas, depending on the sound volume and frequency. This enables sources of irritating noise and its distribution to be identified and examined.

During the development of the new CL-Class this innovative aero-acoustic measuring procedure was supplemented with well-proven artificial head technology: a dummy with an artificial head, whose anatomically accurate auditory passages were equipped with capacitor microphones, was seated behind the steering wheel. These made both spatial sound recordings and precise measurements of sound pressure and frequency possible.

Subsequent evaluation of the test results showed how effective the noise reduction methods were. The acoustically sensitive area at the driver’s head level appears as a blue, particularly quiet zone on the computer screen of the parabolic mirror microphone system. At a wind speed of 140 km/h, the interior noise level in this area is below 66 decibels.

Background noise subjectively perceived as pleasant

In addition to taking measurements, Mercedes engineers also consider it important to establish how male and female drivers perceive the level of acoustic comfort. This is because some noises which the equipment registers as quiet can in fact be irritating, and compromise comfort on long journeys. They therefore use analytical methods which better reflect human audio-perception and provide key psycho-acoustic information about subjective perception of background noise.

One of these parameters is loudness, for example. This is calculated on the basis of different frequency groups, and is better able to describe how humans perceive loudness than the noise level in decibels. At a wind speed of 140 km/h, an outstanding result of just 19 sone was measured in the new CL-Class. Other criteria for noise comfort include harshness, which predominantly evaluates high frequency noises such as hissing or whistling, and the articulation index. This indicates how easily the car occupants are able to converse during a journey. For example, it is irritating if the airstream creates a continuous, high-frequency rushing sound which makes conversation more difficult.

Mercedes engineers arrived at an articulation index of 78 percent for the new CL-Class. This is more than ten percentage points above that of the preceding model, and significantly exceeds the value for other cars in the luxury class. The ideal conditions are therefore in place for easy communication between the driver, front passenger and rear seat occupants.

Hearing tests with 60 male and female drivers confirmed the effectiveness of these aero-acoustic developments in the new Mercedes Coupé. They were asked to evaluate certain noises, and thereby helped the engineers to achieve favourable aero-acoustic values.

Windscreen wipers: aero-technology with two motors

The windscreen wipers of the new CL-Class were also developed in the wind tunnel: they are known as aero-wipers. Instead of the articulated retention system used for conventional wiper blades, in which the rubber blades are claw-mounted, the aero wiper consists of a one-piece rubber section with an integral spoiler and externally mounted spring rails; these precisely follow the curve of the windscreen. The spring rails ensure an even distribution of wiper pressure along the entire length of the wiper blade, so that it always operates with the greatest possible contact pressure. The result is significantly better wiping quality, while wiper noise is considerably reduced.

The wipers on the driver and front passenger sides are powered by two motors, and have different kinematics: while the driver’s-side wiper arm moves around a fixed axis, its counterpart on the passenger side executes an additional lifting movement to wipe an even larger area of the windscreen. The rain sensor which controls the windscreen wipers according to rain intensity is standard equipment, and can be adjusted in two sensitivity stages using the multifunction stalk on the steering column.

Windows: silver foil as an infrared reflector

The new CL-Class leaves the production line with infrared-reflecting, laminated glass which also has an invisible coating of pure silver. This not only filters out UV radiation, but also light in the infra-red spectrum which is mainly responsible for heating up the interior. Compared to green-tinted glass, this reduces the energy radiation into the interior from 60 to around 47 percent at the windscreen.

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Support systems

In 1998 a long-held dream for many drivers was fulfilled with the Mercedes-developed DISTRONIC proximity control system: an electronic co-pilot which keeps the car at a set speed and at a set distance from the vehicle ahead – for more convenience and less stress. Mercedes-Benz has now developed this highly efficient support system even further, hence the name DISTRONIC PLUS.

By combining the previous DISTRONIC radar (77 GHz) with a newly developed close-range radar (24 GHz), which is also used for Brake Assist PLUS, Mercedes engineers have been able to extend the working range of the proximity control system even further, so that it can now scan a distance of anything from 0.2 to 150 metres. While the 77-Gigahertz radar monitors the road ahead over a long distance, the signals from the 24-Gigahertz sensors have a range of around 30 metres and monitor the immediate vicinity of the vehicle. The electronic control unit analyses the information received from both radar systems and calculates the engine, automatic transmission and braking parameters required for proximity control.

In addition, the speed range for this control function has been increased from the previous 30 - 180 km/h to zero - 200 km/h. This means that when the traffic tails back, DISTRONIC PLUS automatically brakes the CL-Class to a standstill and accelerates back to the set speed as soon as the traffic situation allows. To move off automatically, the driver only needs to operate the DISTRONIC stalk on the steering column or briefly depress the accelerator.

As before, the required interval can be set according to the traffic flow and density: using a control function on the DISTRONIC stalk, the driver is able to variably adjust the time lapse between one and two seconds if required by the traffic situation. The medium setting corresponds to a time lapse of 1.5 seconds, representing a gap of around 42 metres at a speed of 100 km/h. The target and actual distances between the CL-Class and the vehicle ahead are shown in the central display of the instrument cluster.

Automatic braking to a standstill

As more dynamic proximity control intervention is often required at lower speeds, i.e. in stop-and-go traffic with frequent starting and braking, the acceleration and deceleration values of the system have been reconfigured. Depending on the speed, automatic deceleration of up to four m/s² (previously two m/s²) is now possible. If DISTRONIC PLUS detects that heavier braking is required, a warning light appears in the instrument cluster. This is accompanied by an intermittent, audible warning which tells the driver to watch the traffic situation and apply the brakes himself if necessary.

The electronic proximity control system can be activated independently of DISTRONIC PLUS. In this case too, the system continuously monitors the distance from the vehicles ahead and gives the driver an audible warning if he is approaching another vehicle too rapidly at a speed of more than 30 km/h, and lights up a warning lamp if the gap is too small.

Parking guidance system: radar technology shows the way into a parking space

A newly developed parking guidance system is celebrating its series production debut in the CL-Class. This uses radar technology to help the driver find a suitable parking space and park the vehicle. When driving past at a speed of up to around 40 km/h, side-mounted radar sensors in the front and rear bumpers of the new luxury Coupé measure whether the parking spaces on the driver and front passenger sides are sufficiently large for the vehicle. Once the system has found a suitable parking space on the front passenger side, a blue "P" symbol appears in the instrument cluster if the vehicle speed is below 16 km/h. Parking spaces on the driver’s side are shown if the indicator on that side is operated.

Once the driver has stopped the Coupé in the position shown on the display and engaged reverse gear, the display shows a symbolic, bird’s-eye-view representation of the parking situation. Coloured guide lines show the driver how best to park: a red line indicates the current steering angle, while a blue line shows the steering angle required for parking. The driver now turns the steering wheel until the two lines coincide, and can then begin to reverse slowly.

As soon as the ideal and actual steering angles coincide, the guide lines on the display change to green. When reversing, an acoustic signal informs the driver when it is time to countersteer.

During the parking manoeuvre, the guidance system continuously monitors the steering angle and vehicle position. If the driver stops before reaching the recommended position, for example, the system automatically recalculates the ideal steering angle for smooth parking.

The new, radar-based parking guidance system, which will be optionally available for the new CL-Class from the end of 2006, works in tandem with the Parking Assist feature familiar from the S-Class. This system uses radar to measure the distance to obstacles in front of and behind the car, informing the driver by means of the display and an intermittent acoustic warning.

The system uses the four close-range sensors at the front and two radar sensors in the rear bumper to assist the driver when parking or warn him of obstacles when reversing. The newly developed system operates with a much greater range and coverage than PARKTRONIC, which is based on ultrasound technology. The radar sensors of Parking Assist operate up to a distance of eleven metres and have a scanning angle of 40 degrees, which means that the driver is warned of an impending collision much sooner. This is an advantage which becomes particularly obvious when reversing over a longer distance. In this case the system is active from a speed of seven km/h, and warns the driver with an audible signal if a collision threatens. This allows enough time to prevent the collision with firm operation of the brake pedal.

When parking the vehicle, the system assists the driver within a speed range from zero to 16 km/h. When moving forward, the colour display in the instrument cluster shows two segments which indicate the distance from an obstacle within the range of the radar sensors on the left and right sides. When the first red segment lights up an intermittent warning is also sounded. A constant warning note is sounded when the second red segment is reached, informing the driver that the minimum distance has been reached. When reversing, a display in the rear roof liner is switched on and indicates the distance from any obstacles – once again for each side of the vehicle and with an acoustic warning over the last few centimetres.

Reversing camera: electronic eye in the boot lid

The new CL-Class can also be supplied with the proven PARKTRONIC ultrasound-based parking system, which assists the driver when parking. A special reversing camera provides further assistance. The reversing camera, mounted in the boot lid above the licence plate, is activated automatically when the driver engages selector position "R". It projects an image of the area behind the vehicle onto the COMAND display. Based on the vehicle dimensions, speed and steering angle, a control unit calculates the optimal path the vehicle should take into the parking slot. Coloured lines are superimposed on the camera image to guide the driver.

LINGUATRONIC: voice control for radio, audio, telephone and navigation

For a number of years now, this Mercedes-Benz-developed voice control system has been establishing itself as an important support system which enhances both safety and convenience. In the new CL-Class, the driver can use LINGUATRONIC (optional) to control the telephone, audio system and navigation system. After activating LINGUATRONIC using a button on the steering wheel, all the driver has to do is say the word - or words - and the radio will search for or store another station, switch to the next track on a CD or enter the desired destination in the navigation system. In this way LINGUATRONIC reduces driver stress, allowing him to devote more attention to the road and traffic conditions.

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Interior

The driver and vehicle form a perfect team in the interior of the new CL-Class. This is made possible by a newly developed control concept adopted from the S-Class, which is based on extensive ergonomic and perceptual psychology studies, and takes into account the findings from many months of acceptance testing conducted with Mercedes customers all over the world.

The key aims in the development of the operating system for the new S-Class were adaptation and integration, i.e. tailoring technology to the needs of people as effectively as possible (adaptation) in order to optimise safety and enhance comfort, and ensuring clearly and logically arranged controls (integration).

Mercedes engineers have moved the infrequently used seat and climate control adjustment functions, which were operated using separate switches or buttons in the outgoing model, into the central control system COMAND. The Sindelfingen-based experts have grouped together other functions, for which switches and buttons are still the most effective solution, into functionally related control clusters. These control clusters can be found in the door trim, instrument panel and roof lining. The principle behind the modifications is "everything in its place".

Rapid access to frequently used functions is a major characteristic of the intelligent control system in the S-Class. This means that the driver is not required to relearn, is able to retain old habits and feels at home immediately. The control system is designed for redundancy: the radio, TV receiver, CD/DVD changer, telephone and navigation system can be accessed either via the new COMAND controller and its menu structure, or directly using buttons. The relevant control buttons are ergonomically located in front of the controller, so that the driver can operate them by feel without having to look down. The "Return" button takes the driver back to the next-higher menu level.

The buttons and controls on both sides of the COMAND controller are just as easily accessible. The buttons on the right switch the system on or off, regulate the sound volume or activate the mute function, while the switch array on the left allows the driver to select the transmission mode and adjust the rear head restraints. As another special feature, there is also an individually programmable button for specific functions chosen by the driver. It can be programmed to operate the rear window blind, activate the interior monitoring and tow-away protection system or repeat the route recommendations given by the navigation system, for example.

Operation of the standard automatic climate control system is also possible in two ways, i.e. on a redundancy basis: using the COMAND controller and menu-based control via the colour display, or by means of an attractively styled switch array beneath the air vents. The COMAND system allows further individual climate adjustments such as air distribution and footwell adjustment.

The new functions which are now also controlled via COMAND include individual adjustment of the standard lumbar supports and multicontour seats (see page 59). The display shows a photo-quality image of the seat with the different air cushions highlighted in colour. These can be individually selected using the controller, then adjusted as required. As before, all other seat adjustments and functions are grouped into clearly arranged control clusters in the doors.

Colour cockpit display with clear menu-controlled functions

The steering wheel and instrument cluster are the primary areas in the newly developed control system. These integrate all the important information and functions required by the driver. The centrepiece is an eight-inch (16 : 9) high-resolution colour display with the latest TFT (Thin Film Transistor) technology for an impressively clear image. There is a graphically animated dial speedometer whose needle is partially overlapped to highlight the information presented by the central display. The graphics computer generates a text bar on the lower edge of the TFT display, where up to seven main menus – depending on the equipment levels specified and – and various sub-menus governing individual settings, displays and control functions can be accessed:

• Trip Odometer and trip recorder, trip computer, range, digital speedometer.
• Navi Directional instructions (indicated by arrows) by the navigation system.
• Audio Radio programme, TV programme, title display for CD player, CD-changer and video DVD.
• Telephone Number dialled, caller number, telephone directory.
• Assistance Distance display for DISTRONIC, proximity warning, settings for reversing camera.
• Service Tyre pressure control, ASSYST PLUS, messages.
• Settings Daytime driving lights, digital secondary speedometer, SPEEDTRONIC, activation of radar sensors.

Five-way buttons on the steering wheel

For rapid selection of these functions Mercedes-Benz has developed the controls on the standard multifunction steering wheel further, using circular, illuminated five-way buttons which the driver operates by light thumb pressure. The relevant selection or setting is confirmed by pressing the "OK" button at the centre of the disc. A separate "Return" button enables the driver to return to the next-higher menu level immediately.

The five-way button on the right of the multifunction steering wheel is used to regulate the sound volume (vertical) and operate the car phone (horizontal). Below this there is an additional button with which the driver can activate the LINGUATRONIC voice control system (optional). A few verbal commands are then enough to operate the car phone, audio equipment and navigation system.

COMAND: screen in the driver’s line of vision

The successful Cockpit Management and Data System – COMAND for short – has undergone further technical development with enhanced styling. The result is a considerable increase in its capabilities. In addition to the familiar telematics and audio units, Mercedes engineers have now integrated various vehicle functions which previously required individual controls. Two new features are immediately obvious:

• The large eight-inch 16:9 colour display, which is now positioned at the same level as the instrument cluster and is therefore even more visible to the driver and front passenger. The display can also be electrically pivoted to the left or right by ten degrees.
• The new aluminium COMAND controller with the handrest trimmed in fine wood (CL 600) or leather (CL 500), which serves as the mechanical and electronic interface between the front occupants and COMAND. The main and sub-menus for the control system are selected by rotating or nudging the controller, which is then pressed to confirm the relevant function. A geared electric motor assists the movements of the controller and provides tactile feedback. The rotary function is automatically locked when the end of a display sequence has been reached, for example. If a car phone is fitted ex factory, the handrest can be flipped up to reveal the telephone keypad.

A new operating structure, up-to-date colours and clear, photo-quality graphics also make the COMAND menu selection procedure a gratifying visual experience. The screen content is horizontally divided into separate areas which are easily accessed using the controller. As in the central display in the instrument cluster, the system is accessed via a menu bar which contains up to five main functions:

• Navi Road map, destination input, destination memory.
• Audio Radio, CD player or changer, DVD audio, MP3, rear entertainment (optional), auxiliary port.
• Tel Telephone, address book, news.
• Video TV reception, DVD video, auxiliary port.
• Vehicle Rear blind, exterior mirrors (convenience settings), easy entry and exit (steering wheel), headlamp switch-off delay, ambient lighting (optional), locator lighting, automatic locking, interior monitoring, tow-away protection, boot lid stop.

Calling up one of the menus activates further menu bars on the lower edge of the COMAND display. When the radio is switched on, for example, these allow additional settings to be accessed, including sound, balance/fader, waveband and a list of stations. The newly designed radio dial clearly displays radio stations, which the driver or front passenger can change by rotating the controller. The usage principle behind the menus is straightforward and easy to get to grips with: functions or lists arranged under the sub-menus are called up by pressing the controller, while elements within the lists are activated by turning the controller or nudging it up or down, then pressing it. To close one of the lists, it is sufficient to move the controller to the side or press the "Return" button in front of the controller.

A radio, CD player and PC card player in one

The COMAND system in the CL-Class combines the latest audio, video and navigation technology. The following functions are included in the standard configuration:

• Radio SW, MW, LW and FM reception. Twin FM tuner with RDS/TMC. Automatic station memory for all receivable radio programmes. 20 station memory presets per waveband.
• Amplifier Four x 25 watts. Ten loudspeakers.
• CD/DVD Single deck for music CDs and for audio or video DVDs. Also for MP3 formats.
• PC cards Slot for PCMCIA cards below the CD/DVD player.

Navigation data on a computer hard disc

COMAND can be ordered with a navigation system as an option (standard for CL 600). In addition to the satellite receiver (Global Positioning System) and yaw-rate sensor, this system also contains a 20-gigabyte hard drive, which allows impressively high-speed access to navigation data and even quicker route planning than with a DVD-based navigation system. During the route guidance procedure, the navigation system provides even more precise information than ever and recommends which lane the driver should get into on a motorway, for example. Audible traffic congestion reports are also an option, meaning that the driver no longer has to read this information on the display and can therefore focus more effectively on what’s happening on the road ahead.

Sound experience based on the latest digital audio technology

The sound system developed specially for the new Mercedes-Benz S-Class is also available as an option for the luxury Coupé. It offers a live-concert-quality musical experience. Mercedes-Benz sound engineers joined forces with audio experts harman/kardon® to introduce technology never before seen in a car and create a whole new three-dimensional sound experience. The system delivers a previously inconceivable, natural 360-degree musical experience for all passengers, whether from a DVD or CD source and from 5.1 surround or normal stereo recordings. The musical signals are distributed via a 600-watt amplifier located in the rear of the Coupé.

Among the factors influencing sound quality are not only signal processing and transmission, but also special, innovative metal matrix loudspeakers. The rigidity-to-weight ratio of their sophisticated membranes is three times greater than conventional loudspeakers. This gives them extra sensitivity.

Dimensional concept: comfort made to measure

As with the control system, Mercedes engineers followed a clear principle when developing the dimensional concept for the interior: the car had to adapt to the people inside it, rather than vice versa. With this aim in mind, they developed an interior whose spaciousness and ergonomics are rooted in scientific research findings. The result for the occupants is an outstanding feeling of space, freedom of movement and long-distance comfort. The new flagship Coupé by Mercedes-Benz is slightly larger than its predecessor: with a length of 5065 millimetres, a width of 1871 millimetres and a height of 1418 millimetres, the body is 75 millimetres longer, 14 millimetres wider and 20 millimetres higher than before. The boot capacity has increased by 40 litres to 490 litres (acc. to VDA measuring method).

Passengers in the new CL-Class thus benefit from even greater spaciousness: elbow room for the driver and front passenger has increased by 54 millimetres, and shoulder room in the rear by 16 millimetres.

Seats: wellness on wheels

With individually adaptable backrest and cushion contours, active ventilation and an innovative massage function, the integral seats of the new Mercedes-Benz CL-Class increase the personal wellbeing of the occupants on long journeys. The seal of approval by an independent jury representing "Aktion Gesunder Rücken", a German organisation which tests products for spine-friendly design, confirms the high quality of the newly developed multicontour seat and its health-promoting effects.

The front seats of the CL-Class are designed as so-called integral seats. All the components of the seat belt system are mounted directly on the seat: the inertia-reel mechanism with belt force limiter, automatic comfort-fit, belt buckle and the upper reversing point for the belt. This ensures that the seat belt is in the best possible position for any seat adjustment, and can therefore carry out its protective function to best effect. Accordingly the seats are important components of the occupant protection system. Thanks to robust seat rails of extruded aluminium sections and their sophisticated, weight-optimised welded construction using high-strength steel, they are able to withstand even the most extreme forces during a crash.

Even the newly developed standard seat provides the driver and front passenger with first-class comfort. The fore-and-aft position, backrest and cushion angle, seat height, head restraint and seat cushion depth are electrically adjustable – independently and variably, so that each occupant is able to choose the best individual seating position. This also applies to comfort and support for the lower back, as pneumatic lumbar supports are also standard equipment for the front seats. These enable the driver and front passenger to adapt the backrest contours to their own anatomy, relieving stress on the back muscles.

The technical construction of the newly developed seats for the CL-Class meets the traditionally high standards of quality maintained by the Mercedes-Benz brand in this area. This means sinus springs with a polyurethane foam pad in the seat cushion and Pullmaflex suspension padding with a breathable natural fibre/rubberised mat in the backrest.

Active seat ventilation even more effective

The seat development specialists at Mercedes are not only concerned with classic comfort characteristics such as the springs and padding, but also with the all-round wellbeing of the car’s occupants. The materials and structure of a Mercedes seat must ensure comfort in all weather and temperature conditions. This is ensured by breathable materials and the high-quality leather upholstery used for CL-Class seats.

Even more climatic comfort is provided by actively ventilated luxury seats, which are standard equipment in the CL 600: miniature fans in the seat cushion and backrest take in cool air at floor level and evenly distribute this via an air-permeable fabric under the surface of the seat. This gentle airflow ensures that the occupants remain cool and comfortable even at high outside temperatures.

Specialists have now improved this technology even further. The heated, actively ventilated luxury seats in the new CL-Class are equipped with even more efficient fan controllers, which regulate likewise improved mini-fans in the seat cushion (4) and backrest (2) of each front seat. The upholstery materials have also been modified to improve the efficiency of the heating and ventilation functions even further. The heating elements are now located directly beneath the seat covers.

New multicontour seat with two additional air chambers

Like active seat ventilation, the multicontour seat is a very successful Mercedes invention which greatly contributes to the high level of long-distance comfort in cars bearing the Mercedes star. Multicontour means that the occupants are able to adapt the contours of the seat to their individual anatomical or comfort requirements. This is made possible by air chambers within the seat padding.

A new-generation multicontour seat is used in the CL-Class. This has even more functions – and therefore provides even greater comfort. While the previous multicontour seat featured seven air chambers, the driver and front passenger are now able to adjust four zones in their seats with the help of nine air chambers. These are ...

• the two side bolsters of the seat cushion;
• the lumbar support, which is also height-adjustable;
• the two side bolsters of the seat backrest;
• the shoulder support.

Thanks to new piezo valves, the pneumatics of the multicontour system operate even more quietly and precisely than before. Moreover, the valves are now in a decentralised configuration and therefore respond more rapidly, which means that for the first time, the multicontour seats can also be integrated into the PRE-SAFE® anticipatory occupant protection system: if PRE-SAFE® detects the risk of a collision, it not only tensions the front seat belts but also inflates the air chambers in the side bolsters of the seat cushions and backrests as a precaution. These bolsters enclose and support the occupants, also increasing the distance to the interior door panels during an impact and enabling the sidebag to fulfil its protective function more effectively.

Lateral support tailored to the driving situation

Customers can enjoy the ultimate in seat comfort by specifying the dynamic variant of the multicontour seat for the new CL-Class (standard in the CL 600). The new, decentralised piezo valves for the air chambers noticeably improve the dynamic function of the multicontour seat by responding more rapidly to steering movements. The pressure and volume of the side air chambers in the seat backrests are adjusted in a matter of seconds according to the steering angle, lateral acceleration and speed of the car in order to offer the driver and front passenger even better lateral support. The chambers respond to the driving situation in hand, the system pumping more air into the chambers on the right-hand side of the backrest in left-hand corners, for example, while the left-hand chambers are given extra air through right-hand bends. This dynamic multicontour function relieves stress on the muscles and thus promotes physical wellbeing.

Separate air chambers for a relaxing back massage

The massage function for the dynamic multicontour seat is also a completely new development by Mercedes specialists. This no longer makes use of the air chambers with which the seat contours are adjusted, but rather a separate package of air chambers which is directly integrated into the seat padding. This means that the individual comfort settings are retained.

A micro-computer controls the seven separate massage air chambers. This inflates and empties the air chambers according to a fixed programme, which passengers in the new CL-Class perceive as a pleasant, pulsing motion across the entire back. This stimulates the muscles, improves the circulation and helps to prevent early fatigue. The massage programme lasts for five minutes and can be restarted at any time once the cycle has finished. The intensity and speed of the massage function can also be individually adjusted, from "slow and gentle" to "fast and powerful".

Climate control: four temperature zones for individual comfort

The numerous series of tests conducted by the passenger car development department at Mercedes-Benz and DaimlerChrysler Research provide clear evidence that a high-performance air conditioning system is one of the most important elements in keeping a driver alert and focused during long journeys. A driver’s powers of concentration and reactions are influenced critically by the climate inside the vehicle.

The automatic climate control system of the new CL-Class is based on the system used in the S-Class since autumn 2005, and meets the highest standards. Each passenger can adjust the temperature in their area of the car individually, the system working according to a new concept based on four independently controlled temperature zones. The engineers refer to upper and lower temperature zones:

• The two lower zones correspond to the air vents in the front and rear footwells and the two central vents in the rear.
• The upper temperature zones include the vents in the centre of the dashboard and the defroster outlets on the driver’s and front passenger sides of the car.

Whereas conventional air conditioning systems work according to pre-programmed stratification of head and footwell temperatures, the new zone concept in the new CL-Class now allows continuous adjustment of the temperature stratification inside the car. Flaps in the climate control unit are responsible for regulating the temperature in the four zones, ensuring a mixture of cold and warm air and thus controlling the desired airflow temperatures. A total of 15 electric motors control these cold and warm-air flaps in the mixture zones, and the air outlet flaps for the vents.

Personalised settings are also possible in automatic mode

The automatic climate control system also offers a range of other individual adjustment options, which the driver and front passenger can select using the COMAND controller and the COMAND display. One example is the footwell temperature. The system features five settings which can be selected to raise the outflow temperature specifically in the footwell area.

Since the definition of what constitutes climatic comfort is highly subjective, even in automatic mode the system in the new CL-Class works according to individual settings and preferences. In addition to individually adjustable footwell heating, there are three different types of ventilation to choose from, which the driver and front passenger can select using the COMAND controller:

• Medium airflow: This setting is equivalent to the previous automatic mode in a Mercedes air conditioning system.
• Diffuse airflow: This mode delivers the lightest possible airflow. The cooled or warmed air is not channelled directly towards the passengers, but flows predominantly out of the defroster vents in the dashboard, the air outlets in the footwells and from the direct ventilation level.
• Focused airflow: In this setting, the automatic climate control pushes out larger quantities of air and channels it mainly through the vents in the direct ventilation level.

In the interests of raising individual comfort levels still further, the air conditioning system in the new CL-Class now allows the driver and passengers to adjust the quantity of air separately for the left and right-hand sides of the car, as well as the temperature and air distribution. They can do this at the touch of a button on the attractively styled dashboard control panel, or by going into the climate control menu bar on the COMAND display.

Sensors for temperature, humidity, solar radiation and pollutants

The system is controlled by a total of eight climate control sensors. As well as outflow temperature sensors in the four temperature zones, the central temperature sensor next to the ignition switch, the solar sensor and the evaporator sensor, the automatic climate control system also uses a special dew point sensor to respond to changes in humidity. Working in conjunction with the fully variable refrigerant compressor, this humidity sensor allows the system to respond as required. Intake air is first cooled according to its humidity, then dried and heated to the desired temperature. The air conditioning system works far more efficiently than conventional systems and offers higher levels of comfort.

In addition, the automatic climate control in the new CL-Class is fitted with a pollutant sensor, which measures the amount of carbon monoxide and nitrogen oxide in the outside air. If pollutant concentrations rise beyond a certain level, the air conditioning system switches automatically to recirculation mode. In fresh-air mode, two combined filters arranged in a "V" are permanently in use. These absorb pollutants, separate out plant pollen and dust particles and reduce irritation for the passengers caused by odours.

Interior lighting: pleasant ambient lighting during the journey

Light is synonymous with safety, but it also influences comfort. The Mercedes engineers took both aspects into account in the development of the interior lighting system for the new CL-Class. In order to ensure that the occupants feel as comfortable in darkness as during the day, the switches and controls benefit from indirect lighting, and the footwells and door handle recesses feature lamps which give off a pleasant amber light. This helps to create a pleasant ambience during the journey. An LED in the rear-view mirror casing also contributes to the interior lighting and is directed towards the centre console.

The diffuse light for the front of the car has five dimmer settings and can be adjusted individually using the buttons on the multifunction steering wheel and the central display in the instrument cluster. The brightness of the front and rear footwell lighting automatically dims when the doors are closed.

Mercedes-Benz is offering a special optional extra (standard in the CL 600) which makes night driving in the CL-Class even more of a special experience: indirectly illuminated wood trim elements in the doors and dashboard. Thin optical fibres located behind the trim strips and illuminated by LEDs generate a harmonious and continuous band of light below the waistline, improving orientation for the passengers and at the same time enhancing comfort and the feeling of spaciousness. The brightness of this ambient lighting can be individually adjusted and is automatically activated as soon as the doors are closed.

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Chassis

In 1999, with the introduction of the predecessor to the new CL-Class, Mercedes-Benz opened up new dimensions in handling dynamics: the flagship Coupé was the world’s first car to feature the Active Body Control (ABC) suspension system. This innovative system has been developed and improved even further for the new CL-Class.

Active Body Control resolves the traditional conflict of aims when configuring a passenger car suspension: should wheel vibrations caused by the road surface be kept to a minimum by a sports, stiff shock absorber configuration, or should the damping be made more comfortable and soft at the expense of handling safety and performance? Thanks to ABC, which is standard equipment in the new CL-Class, this conflict of aims is a thing of the past: the suspension configuration is automatically adapted to suit the current driving situation. A high level of comfort is accompanied by dynamic performance - or vice versa.

To this end, the four spring struts are equipped with microprocessor-controlled plunger cylinders which almost completely compensate yawing, pitching and rolling movements of the vehicle body. The computer receives information about the relevant driving situation from the various acceleration sensors, then compares this with the data from the pressure sensors in the spring struts and the level sensors in the steering control arms. The ABC system translates this information into control signals, which are implemented as precisely metered oil flows by hydraulic servo-valves on the front and rear axles. When oil flows into the plunger cylinders, these adjust the tracing point of the steel springs integrated into the spring struts, generating the forces necessary to counteract movements of the vehicle body.

Under pressure: body is stabilised within fractions of a second

Owing to the constantly available hydraulic pressure of up to 200 bar, ABC is able to stabilise the vehicle body immediately - in fractions of a second. The system operates in the vibration range up to five hertz, the range which causes pitching and rolling movements on uneven road surfaces, side-roll on bends and the typical body dive experienced during braking. Higher-frequency vibrations and wheel damping are the responsibility of passive twin-tube gas-pressure shock absorbers, which can be configured for excellent comfort.

Every component in the active suspension control system has been revised for the new CL-Class. The specialists have now arranged various components into groups, in order to improve the control functions with shorter connecting lines and reduce the installation space required.

On fast bends: body roll reduced by up to 45 percent

The major advantage of second-generation Active Body Control is its greater efficiency in reducing body movements according to the driving situation: the body roll angle during a dynamic driving manoeuvre is reduced by more than 45 percent – from the previous 2.2 to 1.2 degrees. When taking bends at speed – for example when leaving a motorway – this second-generation ABC suspension reduces the roll angle to just 0.7 degrees.

Other special features of Active Body Control include variable anti-roll control between the front and rear axles, which the system carries out automatically as a function of vehicle speed to combine agile handling with outstanding stability. The system also takes the vehicle load into account: on the basis of the plunger and spring travel, the ABC computer calculates the actual vehicle weight and takes it into consideration for the active control function.

At the touch of a button: individual suspension and transmission characteristics

In addition the new CL-Class features an S/C/M button in the centre console with which the driver is able to modify the overall characteristics of the Coupé from "comfortable" to "sporty":

• Comfort: In this mode the automatic transmission changes the gears at lower engine speeds, and the CL Coupé moves off in second gear. The ABC suspension operates in Comfort mode, comfortably smoothing out uneven road surfaces and bumps.
• Sport: The automatic transmission makes full use of the engine speed range in this setting. The ABC suspension operates in Sport mode, with a stiffer damping effect on uneven surfaces and bumps. The characteristic map of the accelerator is also modified, so that the engine responds more rapidly when acceleration is required.
• Manual: The automatic transmission is operated manually using gearshift buttons on the steering wheel, with significantly reduced gearshift times compared to "Sport" mode. The suspension configuration selected by Active Body Control is the same as in Sport mode, as is the characteristic map of the accelerator.

If the CL-Class is travelling on poor roads which make a higher ground clearance advisable, the driver is able to raise the suspension by 45 millimetres at the touch of a button. When travelling at high speed in Sport mode, ABC automatically lowers the suspension by up to ten millimetres to reduce aerodynamic drag and lower the fuel consumption.

Front axle: four-link technology improved even further

In addition to improving the ABC system, the Mercedes development engineers turned their attention to the choice of axle designs for the new luxury Coupé. The results of digital design and test procedures, as well as exhaustive practical trials, confirmed them in their view that four-link technology offers the greatest advantages for the front axle. Accordingly this was refined in detail – especially where comfort is concerned.

Wheel location at the front is by means of a so-called high-link axle. This consists of an aluminium wishbone at the upper level, a lower aluminium torque strut and a spring link of forged steel. The two levels are connected by steering knuckles. The fourth component, the one that gives the four-link axle its name, is the track rod; this creates the link between the front wheels and the transverse rack-and-pinion steering system.

Another major advantage of the Mercedes four-link axle is the design of the lower link level. This provides favourable axle kinematics, and is almost completely insensitive to vibrations caused by unbalanced tyres or fluctuations in braking force. It was on this positive basis that the engineers reconfigured the kinematics and elasto-kinematics of the new CL-Class, with a great improvement over the preceding series. Safety specialists at the Mercedes-Benz Technology Centre provided another important reason for choosing the four-link system: in a frontal crash it offers longer deformation paths at the lower link level than other axle designs, and is therefore able to absorb kinetic energy more efficiently.

Compared to the preceding model, the wider track (front + 24, rear + 29 millimetres) and the longer wheelbase (+ 70 millimetres) create other important conditions for the even better ride comfort and exemplary handling dynamics of the new CL-Class.

Steering: mid-centred for safe, stable handling

As before, the steering gear is located in front of the wheel centre and therefore supports the easily controlled understeer characteristic of the luxury Mercedes Coupé on bends. The servo-assisted rack-and-pinion steering has a variable ratio (50.1 to 60.5 millimetres per turn of the wheel), which is slightly more indirect in the mid-range than in the outer positions. The lower the vehicle speed, the greater the servo-assistance: below 200 km/h the steering effort is continuously reduced depending on speed, which means that the driver only needs to exert one third of the maximum steering effort when parking at low speed.

Variable mid-centring is a new feature in the CL-Class: the electrohydraulic, speed-sensitive servo valve is used to create a centring force which increases with the vehicle speed and gives the driver a feeling of safety and stability in the centre position. This additional steering force is not activated when the vehicle is at a standstill, enabling the advantages of the speed-sensitive steering to be fully exploited.

The telescopic steering column is electrically adjustable for height and reach, and also provides an automatic entry/exit aid as an additional convenience feature: once the driver has withdrawn the electronic ignition key, the steering wheel moves upwards to provide more legroom. The wheel then remains in this position until the key is reinserted into the ignition lock, when it returns to its preset position.

Mercedes-Benz has developed a four-spoke steering wheel with a diameter of 390 millimetres for the new CL-Class, whose diecast magnesium structure specifically deforms during a frontal impact to reduce the risk of injury to the driver. With its ergonomically located, illuminated control buttons, the steering wheel is a major component of the operating system in the new CL-Class. An electrically heated steering wheel is available on request.

Rear axle: made completely from aluminium

Because multi-link axle technology remains unsurpassed, the engineers at Mercedes have remained faithful to it in the new CL-Class, but have made certain detailed improvements: the rear axle housing is derived from the previous unit as an aluminium construction which is open to the front and features a bolted front cross-member. The major advantages of this new sub-assembly are lower weight, greater strength and more compact dimensions.

The use of uncompromising lightweight construction methods has enabled Mercedes engineers to reduce the weight of unsprung masses at the rear axle considerably, thereby improving both handling and ride comfort. Four of the five links are of forged aluminium, while the spring link is of single-skin sheet aluminium and the wheel carrier is of diecast aluminium. The rigidity of the wheel-locating components has also been increased.

The specialists in Sindelfingen also gave their attention to insulating vibrations which might be transmitted from the final-drive unit to the vehicle interior via the axle housing. Three large rubber bearings were developed to minimise this effect.

Braking system: high-tech for outstanding safety and comfort

ADAPTIVE BRAKE – this newly developed braking system familiar from the S-Class is also standard equipment in the new CL Coupé. It allows electronic control of the hydraulic, dual-circuit braking system and provides a number of support functions for additional safety and comfort:

• HOLD: Once the luxury Coupé has been braked to a stop, briefly depressing the brake pedal a little further activates this function. The CL-Class is then held in position by the brakes – even when the driver removes his foot from the brake pedal. In this way the HOLD function prevents the vehicle from rolling forward unintentionally at traffic lights or in stop-and-go traffic.
• Hill holder: With this auxiliary function, ADAPTIVE BRAKE prevents the CL-Class from rolling backwards when the driver switches from the brake pedal to the accelerator to move off on an uphill gradient. When the sensor system detects that the Coupé has come to a stop on a gradient, the hill holder function is activated automatically and maintains a constant brake pressure for a short time to make moving off easier.
• Priming: The braking system interprets rapid removal of the driver’s foot from the accelerator as an emergency braking situation. In this case ADAPTIVE BRAKE increases the pressure in the brake lines and brings the brake linings into light contact with the brake discs, so that they are then able to bite immediately and with full force when the brake pedal is depressed. In this way the system supports the functions of Brake Assist and Brake Assist PLUS.
• Brake drying: In the wet ADAPTIVE BRAKE applies regular, brief braking impulses to wipe the film of water from the brake discs and ensure that the brakes are able to perform at their peak. The automatic brake drying function is always activated when the windscreen wipers of the CL-Class have been operating for a certain time. The driver does not notice the finely metered braking impulses.

Large-diameter front and rear brake discs create the technical basis for reliable deceleration with ADAPTIVE BRAKE. Depending on the engine version, their diameter is up to 360 millimetres at the front and up to 330 millimetres at the rear. The front brake discs are perforated. The perforations conduct water and dirt away, ensuring that the brakes operate reliably and with good deceleration performance in poor weather conditions.

Parking brake: electric motor for added convenience

The new CL-Class is equipped with an outstandingly convenient, electric parking brake as standard. The brake is activated by simply pressing a button on the dashboard. The brake is automatically released as soon as the driver selects a gear and moves off. The major components of this new development are two separate servo drum brakes at the rear wheels and an electric motor with a reduction gear, which applies the brake drums by means of cables. The electric parking brake can also be applied when the engine is switched off.

Dynamic safety systems: new functions for even better performance

ABS, ASR, ESP®, Brake Assist – these well-proven dynamic safety systems developed by Mercedes-Benz are standard equipment in the new CL-Class, and now have a number of additional functions.

Mercedes engineers have enhanced the anti-lock braking system (ABS) with additional technology that makes braking even safer on surfaces which are slippery on one side. The system recognises these situations and controls the brake pressure in such a way that the driver is given optimal assistance in staying on track and braking efficiently. The ABS system in the new CL-Class also ensures more safety when braking on bends, as it distributes the braking forces to create a yawing moment which counteracts and stabilises the vehicle’s tendency to break away. The braking system uses data supplied by the ESP® sensors to detect these situations reliably.

The Electronic Stability Program also improves the functions of acceleration skid control (ASR): ESP® sensors supply online information about the slip at each wheel and enable the traction control to be activated even more precisely, particularly allowing much better progress on icy roads. What is termed “snow-chain logic” is another enhanced ASR function. On the basis of the drive torque and driving resistance, this system automatically detects whether snow-chains have been fitted and adapts the acceleration skid control accordingly.

When taking fast bends, a yaw moment control system now registers the stiffness of the tyres and improves ESP® control intervention if the CL-Class is fitted with winter tyres. The new, electronically controlled braking system ADAPTIVE BRAKE offers additional advantages because the brake servo unit is selectively controlled by electronic means, allowing ESP® to operate particularly sensitively and comfortably. The system is also faster and more efficient than before: ESP® automatically reduces the distance between the brake pad and the brake disc if there is a risk of skidding and the CL-Class needs to be stabilised by specific braking impulses.

Tyre pressure loss warning as standard

Tyre pressures are monitored by the Electronic Stability Program ESP® or a special control system based on radio technology:

• ESP® continuously compares the wheel rotation speeds, which mainly depend on the vehicle speed, vehicle load and tyre pressures. 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. It is therefore able to detect any significant deviations and inform the driver via the central display: "Tyre pressure, check tyres". This tyre pressure loss warning system based on ESP® technology is standard equipment in the CL-Class.
• An optional electronic tyre pressure monitoring system is also available; it uses sensors in the tyre valves to monitor both the air pressure and temperature inside the tyre. The data are transmitted by radio to a special underfloor aerial at regular intervals. Intelligent software is used to identify the wheel positions automatically, so that the driver can be given specific information about the air pressure in each tyre via the central display.

To ensure continued mobility in the event of a flat tyre, Mercedes-Benz also offers run-flat tyres as an optional extra. These have self-supporting walls, and enable Mercedes customers to continue for a distance of up to 100 kilometres at a maximum speed of 80 km/h despite the flat tyre.

Safety

Engines