2007 Citroen C6
The Citroën C6 has arrived. The latest addition to a historic line of great Citroëns, with a stunning look in keeping with the Marque’s reputation for style, the C6 takes the grand tourer concept and incorporates the latest cutting-edge technology.
2007 Citroen C6
Horsepower @ RPM:215 @6,000
Torque @ RPM:290@3,750
0-60 time:9.3 sec.
Top Speed:142.9 mph
The C6 adds the crowning touch to a wider and more complete Citroën range, extending from the C1 to the C8. The presence, styling and executive features of the C6 clearly identify it as an executive model. It is a car inspired by great Citroëns of the past – the DS, CX and SM – whose design and innovative technologies have helped the Marque to establish a strong heritage in large cars.
The C6 takes the essential cues of executive saloons – elegance, sophistication and on-the-road presence – and combines them with the Marque’s own key values. Derived from classic Citroëns and continuously updated, these values are expressed through avant-garde technology, based on styling and the pursuit of comfort, and through engines that place the emphasis on driveability rather than sheer power.
Through its fluid and dynamic styling, the C6 is a highly distinctive car. Depending on the angle from which it is viewed, its unique styling brings to mind an elegant coupé or an executive limousine.
The exceptional on-board comfort takes the driver and passengers into a world of opulence. The roomy, spacious passenger compartment uses premium materials.
The driver’s position, in particular, gives new meaning to the concept of ergonomics. Driving information is clear and precise. The read-out can also be shared with passengers by tilting the central screen located in the top part of the dashboard.
Key safety features include a height-adjustable head-up display, allowing the driver to concentrate on the road ahead, a lane departure warning system (LDWS) and xenon dual-function directional headlamps.
Once again, Citroën has proved its ability to achieve continuous innovation.
The C6 is a global concept, a balance of unique design lines and advanced technology creating an impression of advanced safety and – of course - comfort.
The C6 combines high levels of passive safety for passengers (active headrests and nine airbags amongst other features) and pedestrians (active bonnet system) with impeccable road manners based on new running gear with active suspension and electronically controlled springing and damping.
The C6 features double wishbone suspension and a linked hub carrier at the front, with a multi-link system at the rear. This set-up gives it real agility, as well as making full use of the V6 petrol and diesel engines available with the 6-speed automatic gearbox.
As a result, the C6 combines precise wheel guidance with impeccable roadholding and perfect handling, whatever the situation.
The C6 is produced at the Rennes site, where dedicated quality teams inspect each vehicle individually.
On the road: impressive dynamic qualities
Whether cornering or driving on the open roads, the C6 fulfils its promise as a grand tourer.
The refined V6 engines and running gear make for exceptional dynamic qualities.
The top-of-the-range positioning of the Citroën C6 is reflected by its engine line-up. Two V6 engines, one petrol and one diesel, place the emphasis on driving pleasure and refinement. The 3-litre petrol engine develops 215 bhp DIN (155 kW), while the new 2.7 litre HDi diesel engine develops 208 bhp DIN (150 kW) and is equipped with a particulate filter. Both engines are mated to 6-speed automatic gearboxes
The C6 is the first car to combine hydraulic suspension with double wishbones at the front and a multi-link set-up at the rear. Associated with an active suspension system featuring electronically controlled springing and damping, the running gear of the C6 effectively soaks up bumps and dips in the road surface to set new standards in comfort, roadholding and driving pleasure.
By separating the damping and steering functions, this set-up offers a response to the eternal conflict between the dynamic capability and the comfort of the suspension.
Innovative, practical equipment for a relaxed drive
Alongside the intelligent driving aids already present on the C4 and the C5 – such as the lane departure warning system (LDWS), front and rear parking assistance, xenon dual-function directional headlamps, cruise control and a speed limiter – the C6 also features a head-up display and an electric parking brake, a first in the Citroën range.
Exceptional on-board comfort
Thanks to its exceptional driving qualities and its exclusive approach to the art of life on-board, the C6 is perfectly placed to continue the line of other great Citroëns. Looking beyond the modern, completely revised driver’s position, each and every feature in the cabin is based on useful technology and contributes to the overall impression of comfort: multi-adjustable seats, acoustic insulation and thermal comfort.
The innovative driving position incorporates an easy-to-read driver’s instrument panel and a head-up display. Adjustable for height and brightness, this display unit projects essential information – on speed and navigation for example – onto the windscreen, thus contributing to active safety. The driver is thereby able to concentrate fully on the road. The exceptionally quiet cabin also contributes to maintaining the driver’s attention.
The user-friendly interior provides the occupants with generous individual space. Passengers in the back can adjust the electrically-controlled sliding rear seats to obtain the ideal relaxed position.
The stowage compartments in the doors, inspired by the latest trends in home furniture design, reflect the pure design lines of the dashboard.
Reflecting Citroën’s efforts to continuously improve passenger well-being, the air-conditioning on the C6 includes a soft diffusion system. This feature is designed to create a uniform blanket of air around the passengers, and to enhance thermal comfort.
Uncompromising on safety
The C6 also aims to be a class leader in safety, in terms of both vehicle control and protection of passengers and pedestrians.
High-level active and passive safety are provided by a range of features, including ESP, a stiff body structure, a knee airbag and active headrests. As a further extension to these safety features, an active bonnet system protects pedestrians in the event of impact.
Original, emotive styling
The original design of the new C6 combines the Marque’s own styling cues with those of an executive car. The proportions, profile and curve of the wheel arches immediately identify it as a large Citroën.
The C6 features a long front overhang and short rear overhang. The design lines and general approach bring to mind both a powerful coupé and a prestige saloon, from the standpoint of their respective qualities.
At the front, the C6 features a wide grille and chrome-plated chevrons spanning the nose right up to the vertical headlamps. The headlamps extend up onto the wings and wide ribbed bonnet.
A long wheelbase and flowing, aerodynamic profile give the C6 real presence, while suggesting space, stability and power.
The windows hug the curve of the roof arch, which in turn blends smoothly into the rear pillars in a subtle nod to coupé styling, an effect that is taken one step further by the frameless doors.
At the rear, the design is particularly eye-catching. The concave window extends down to the boot lid and lighting functions, thus adding the finishing touch to the body style. An air deflector is deployed automatically at speed, illustrating the attention paid to another key Citroën value: aerodynamics.
The interior of the C6 creates an immediate impression of space and comfort. The pure lines of the dashboard, premium materials, and comfortable, sculpted seats are an invitation to step on board and enjoy a relaxing ride.
Classic and yet thoroughly original, the C6 sets itself apart from the models that currently set the standard in the sector, while meeting all the requirements of an executive car: elegance, refinement and presence.
On top of all this, the C6 adds Citroën’s own unique stamp, combining strong emotional appeal with the application of cutting-edge technology. Once more, Citroën is showing itself to be a front runner in design, safety and comfort.
A production line appropriate for an executive car
The C6 is produced at the Rennes site, a production centre dedicated to the mid- and top-range vehicles of the PSA Peugeot Citroën Group.
The C6 is based on platform 3, first used for the C5 and subsequently adapted to this new model. The platform features a long wheelbase with running gear specific to the C6, and active suspension with electronic springing and damping.
Resources have been optimised for moderate production volumes. The Rennes site will have a production capacity of around 100 C6 vehicles/daily, or a total of 25,000 units over a full year.
Because the C6 is an executive vehicle, a significant period of time was set aside for development studies. This allowed engineers to devote the necessary care and attention to questions of industrial production.
For the C6, special assembly procedures have been put in place at each stage of the production process, such as individual adjustment of the door windows and suspension, and function checks on each vehicle. The body assembly shop conducts intermediate checks on incoming stamped parts, most of which are produced by suppliers specialising in small volumes and executive vehicles, and devotes many hours to obtaining a perfect fit. At the same time, the number of suppliers is deliberately kept down.
Also, each car undergoes track testing to make sure that all the functions (acoustic comfort, suspension comfort, etc.) are up to standard.
The final assembly workshop dedicated to the Group’s executive vehicles has been specially laid out for moderate output. Also, considerable efforts have been made to improve the working environment.
Exterior and interior design
A symbol of Citroën’s expertise, the C6 joins the select circle of French executive saloons. It has the emotional appeal required by true connoisseurs of exceptional cars.
The C6 resembles a powerful coupé, through its design lines and general approach, and a prestige saloon, through its interior space and generous functions.
The C6 is a distinctive vehicle of majestic allure, with a front end suggesting power and prestige, a flowing, aerodynamic profile and an original rear end conveying an impression of confidence and stability.
A front end suggesting power and prestige
The elegant, taut lines and harmonious styling of the C6 have a strong and immediate appeal.
Viewed from the front, the C6 conveys an impression of power with its low-slung stance and large bumper featuring an integrated air intake between the two round fog lamps and daytime running lights.
The wide front end is accentuated by the chrome chevrons that extend to the slim headlamps, as on other Citroën vehicles. The originally shaped headlamps provide a link between the bumper, the wings and the long, smooth curved forms of the bonnet. Designed to incorporate the side lights they extend up onto the wings of the car.
The separation between the headlamps, daytime running lights and fog lamps give the Citroën C6 a piercing, determined gaze.
The shape, parallel lines and contours of the front end reveal strength and nobility, reminding us that the C6 is a unique work of design.
A flowing, aerodynamic profile
The main features of C6 design are flowing lines, energy, aerodynamics and elegance. The body is characterised by a long front overhang and short rear overhang.
The design and shape of the C6 reflect the emotional appeal of an elegant, dynamic coupé with the proportions and features of an executive limousine.
The attractive, imposing profile of the C6 is showcased by its generous dimensions – 1.86 m wide, 1.46 m high and 4.91 m long, with a 2.90 m wheelbase.
The size of the cabin, which is placed well back, is determined in part by the long front and rear doors and by the large glazed area, which lets the light flood in. The effect is further enhanced by the windows on the frameless doors – a nod to prestige coupé design.
To ensure a flawless finish, these door windows are adjusted individually at the C6 production site at Rennes. This high-precision operation takes place in two-stages. Before being fitted on the car, the doors are placed on a preparation line for the initial adjustment of the windows. When the doors have been mounted on the car, the windows are adjusted for the second time. This time, the operation is manual to ensure a flawless fit.
The doors underline the overall impression of elegance conveyed by the flowing profile of the C6. The quarter window is partially integrated with the rear door, thus extending the line of the body, and adding a further touch to the car’s natural flowing design.
The harmonious design is also expressed in the high, clearly marked waist line – reinforcing the impression of safety – and in the roof line whose contours run the length of the body, to touch the concave window at the rear.
The profile of the C6 alternates taut, radical lines with rounded, more natural shapes. The wings house large-diameter wheels. The proportions and dynamic design of the wheels fill the wheel arches, creating an impression of power and agility allied with strength and endurance.
As a further touch of refinement, the lower body is smartly finished off by a chrome strip that extends to the rear bumper. This original design reflects the pursuit of new styling effects.
Original rear end design, innovative styling
The C6 features a rear end whose unique styling nevertheless reflects the Marque’s style cues.
Like all large Citroën cars, the C6 is fitted with a concave (reverse curve) rear window. Looking beyond its originality, the concave shape highlights the generous size of the boot.
Discreetly integrated at the top of the tailgate, a deflector deploys automatically at high speeds, contributing to vehicle stability and reducing stopping distances in high-speed braking.
The coloured rear lights are slightly offset. They curve over the rear wings to touch the roof arch.
Looking beyond styling impact, the shape of the lights is also linked to their layout. Each light marks the intersection of the boot, the flanks and the concave rear window.
Another key characteristic of the determined and powerful-looking rear end is the design of the rear pillars whose generous flanks protect the tailgate and partially conceal the boot. The powerful design of the front and rear ends visually stabilise the car.
A chrome strip marks the separation between the tailgate and rear bumper. Emphasising the width of the body, it encompasses a chrome-finished twin exhaust, conveying an impression of strength and power.
This user-friendly approach to comfort is expressed by the presentation of the spacious cabin, in which the various functions are clearly laid out.
The front end houses a symmetrical dashboard organised around a central half-moon console.
The clean, sculpted design of the dashboard is made up of straight and parallel lines, symbolising precision, and curved lines, symbolising dynamics. The styling is both fluid and simple.
The upper part features a multifunction screen, which is almost an echo – or a natural extension – of the console.
In front of the driver, a discreet digital instrument cluster is positioned in such a way as to avoid reflections of light that could make the information difficult to read.
In addition to the information displayed on the central screen concerning the audio system, air conditioning, navigation and other functions, a head-up display projects essential driving data onto the windscreen. The cruise control and speed limiter functions are integrated in the spokes of the steering wheel. The electric seat controls, installed in the door panels, are intuitive to use, since their layout reflects that of the seat.
>An electric parking brake frees up the central console, which includes a number of stowage compartments, and creates additional cabin space.
An airy, well designed interior
The space, colours, premium materials and high-quality finish of the cabin set a high level of onboard comfort . Black leather (Mistral interior), beige leather (Wadibis interior), chrome and wood create a warm atmosphere.
A horizontal strip made of precious wood separates the top and lower parts of the dashboard. Many other features contribute to creating an uncluttered, natural atmosphere that places the emphasis on comfort and well-being. Passengers feel that they are travelling in a modern ’lounge" stripped of superfluous detail.
The seats and door inner panels are covered in high-quality leather that is pleasant to look at and to touch.The curved contours convey an impression of refinement.The closed stowage compartments in the four doors feature precious wood lids whose half-moon design picks up the dashboard theme to maintain styling integrity.
The large glazed area lets natural light flood in and creates a sensation of space that considerably improves comfort during long journeys. At night, side lighting from the door panels creates a relaxed atmosphere.
The on-board comfort of the Citroën C6 is based on the use of advanced technology. More than an invitation to travel and promise of driveability, this high-tech input ensures a particularly relaxing driving experience.
Comfort and choice for all the passengers:A spacious interior
With a wheelbase of 2.90 m, the C6 is designed to satisfy executive saloon customers looking for outstanding space.
At the front, finding the ideal driving position is easy, since the seats can be electrically adjusted in three or five directions and the steering wheel adjusted for height and reach
The flat floor pan at the back increases the impression of space, and considerably improves the space available. The C6 has a cabin length of 1.83 m.
With the Lounge Pack, rear passengers gain two individual seats that are electrically adjustable for an ideal seating position. To increase leg room, the rear right passenger can also adjust the fore-and-aft position of the front passenger seat, using the controls on the side of the rear central armrest. Leg room can thus be increased by up to 995 mm.
The many perfectly integrated stowage compartments placed around the passenger compartment also contribute to the generous space and clearly illustrate the car’s functional qualities.
The C6 has a boot capacity of 488 litres, with a 60:40 split/fold-rear seat. On versions equipped with the Lounge Pack, the boot volume is 470 litres.
The comfort of a high-spec vehicle
The seats accommodate all the occupants of the C6 in comfort, providing excellent postural support for long journeys.
In order to accommodate passengers of all sizes, the electric front seats can be adjusted in different directions: fore-and-aft, height and rake, and lumbar support. These settings can all be memorised, together with those of the exterior rearview mirrors and head-up display.
The active headrests of the driver and passenger pivot forward in the event of rear impact.
The high-quality seats also bring benefits for passengers at the rear. The Lounge Pack includes premium comfort individual seats featuring a heating function.
These seats are electrically controlled for an ideal relaxed seating position.
Class-beating acoustic comfort
Laminated side windows filter out wind noise and exterior noise to provide high-level acoustic comfort. They also contribute to the security of the Citroën C6, which has gained a five-star rating from Thatcham.
The laminated side windows with reinforced acoustic insulation are made up of two sheets of glass, assembled using plastic films of excellent acoustic properties. This system absorbs sound vibrations over a wide range of frequencies, offering an excellent level of performance in terms of sound insulation.
Made of glass and plastic, these windows are virtually impenetrable. This prevents injury in the event of breakage, as well as providing a barrier to stop people or objects from being thrown out of the car in the event of an accident. It also offers efficient protection against vandalism and break-ins.
Insulation: a key factor in acoustic comfort
Alongside the laminated side windows, other features also contribute to interior soundproofing, such as the dash cowl, active engine mounts, and the hydro-elastic mounts of the rear cross-members.
Outstanding acoustics and vibration control create a peaceful atmosphere in the cabin, for the pleasure and comfort of both driver and passengers.
For this reason, each car undergoes testing on a track simulating various extreme conditions (cobbled areas, bumps, etc.) to make sure that all the functions (acoustic comfort, suspension comfort, etc.) are up to standard.
Excellent thermal comfort
High-performance air conditioning
The pleasure of driving and travelling is indissociable from the exceptional thermal comfort enjoyed by all passengers. The C6 features fully automatic air conditioning.
This two-zone system provides individual comfort for occupants at the front. The driver and front passenger can modulate the temperature and air flow independently.
At the rear, a relay blower lets passengers adjust the air flow and create a uniform temperature more rapidly.
The C6 is fitted with a soft diffusion system.
This system is designed to create a uniform blanket of air around the passengers, providing exceptional thermal comfort with no draughts. This ensures a less aggressive air flow, with the air being diffused through the front air vents and rear blower.
High-tech communication equipment
To increase on-board comfort, the driver can install a range of high-tech equipment including:
- the NaviDrive telematics system for stress-free driving,
- the Bluetooth hands-free telephone system to make and receive calls safely,.
- the JBL hi-fi system for high-level acoustics.
A high-performance NaviDrive system
The C6 is available with the new-generation NaviDrive telematics system.
This system comprises three essential functions: a GPS navigation system, a GSM dual-band hands-free telephone with access to the address book and audio system (radio and 6-CD stacker), together with voice synthesis and voice recognition features.
At the same time, passengers can use the screen or voice synthesis function to read SMS messages received over the phone.
The main functions can be accessed easily using the steering-wheel controls, which can also be used for the voice recognition and synthesis functions. NaviDrive can be controlled by the user’s voice without any preliminary learning time. This feature is very useful for making phone calls, finding your way, or accessing the address book without risk. The system can also be operated directly using the unit built into the dashboard. The functions are displayed on a large 16:9 colour screen.
NaviDrive can provide traffic information via a written or voice message as well as giving access to customer services such as Citroën Emergency, Citroën Assistance and Citroën On Line (depending on the country).
Working with the GPS and telephone functions, Citroën Emergency makes it possible (depending on the country) to locate the vehicle if the driver has an accident or is ill, for example, and to access the services of a call centre.
Bluetooth, to make and receive telephone calls safely
The C6 can be equipped with a Bluetooth hands-free telephone in which the address book is displayed on the multifunction screen. This hands-free telephone system, based on Bluetooth wireless technology, is integrated with the passenger compartment.
Bluetooth is a convenient and safe option for making personal in-car calls from a mobile phone, since the driver can make and receive calls without taking the phone out of his or her pocket. In this way, the driver keeps both eyes on the road and both hands on the wheel.
A high-level performance with JBL hi-fi
JBL, one of the world’s leading audio specialists, has developed a hi-fi system specially for the C6. The new system is designed to provide customised acoustics for a top-end vehicle.
The hi-fi system comprises twelve loudspeakers in ten locations, together with a 240 W amplifier. To provide customised sound, each loudspeaker is controlled independently by the amplifier, in line with precise acoustic settings defined specially for the interior of the C6.
Driver and passengers enjoy excellent sound quality, with optimised acoustic reproduction and sound distribution in all circumstances.
Driving and technology
State-of-the-art engines:The C6 is available with two V6 engines, each mated to a 6-speed automatic gearbox, and continuously variable hydraulic power steering.
Both engines offer a smooth ramp-up in power with remarkably quiet running.
Petrol engine: 3.0i V6 developing 215 bhp DIN
This engine features similar technology to the 3.0 V6 fitted on the C5, with 2% more power (+ 3 kW) and torque (+ 5 Nm). It delivers 155 kW EEC (215 bhp DIN) at 6,000 rpm and 290 Nm of torque EEC at 3,750 rpm.
This engine is fitted with a new exhaust line and dual-mode active silencer, which improves both performance and acoustics. By redirecting the exhaust gases through the silencer, depending on driving conditions, this system improves engine acoustics in normal conditions of use and improves performance under load.
In terms of environmental protection, the V6 engine meets the Euro IV emission standard.
Diesel engine: 2.7 V6 HDi DPFS developing 208 bhp DIN
This new V6 diesel engine combines power and fuel economy. It was developed as part of the cooperation between the PSA Peugeot Citroën Group and Ford Motor Company. Delivering a responsive performance from the lowest engine speeds, it develops 150 kW EEC (208 bhp DIN) at 4,000 rpm and torque of 440 Nm EEC at 1,900 rpm. This is an engine that combines smooth, gradual power with exceptional operating comfort.
With capacity of 2,720 cm3, this engine features four overhead camshafts and 24 valves, along with common-rail direct multi-injection and two variable-geometry turbochargers.
The cast-iron cylinder block, aluminium bearing retainer and composite cylinder-head cover make the engine smaller, stiffer and lighter.
Through its advanced design, this V6 engine satisfies the Euro IV emission standard. It is equipped with a new-generation particulate filter, which now needs replacing only every 180,000 km.
Driving pleasure is enhanced not only by these two engines but also by their new 6-speed automatic gearbox. Smooth gear changing ensures a level of driveability that is commensurate with the C6’s ambitions.
Featuring the latest Citroën technology, the C6 aims to set the standard in roadholding and comfort. The emphasis is placed on active safety and driving pleasure.
Particularly efficient running gear
The C6 boasts impeccable road manners, based on an original combination of sophisticated running gear and an active suspension system featuring electronically controlled springing and damping. This exceptional set-up offers a response to the eternal conflict between the dynamic capability and the comfort of the suspension.
Superlative road manners and steering comfort demand careful body control and thus a firm suspension, a set-up that impacts on vertical comfort.
They also require precise control of the wheel position and thus fairly stiff axle bushes, a set-up that makes it more difficult to provide the damping necessary for effective vibration control.
To separate these functions and thus eliminate their mutually antagonistic effects, the C6 implements innovative technical solutions to set superlative standards in every respect.
The first step is to separate the damping and steering functions. The front and rear suspension is of sophisticated design with special bushes that are able – by virtue of their architecture and functional characteristics – to manage the force transmitted to the body in specific ways.
The second step involves analysing each driving situation and managing it in consequence. Here, the emphasis is on body control and vertical comfort. The active suspension with electronic springing and damping comprises two stiffness settings and 16 damping settings. This makes it possible to manage the suspension in real time, in order to adapt to a full range of driving situations.
Principles applied to the optimisation of comfort
Generally speaking, the comfort of a vehicle is defined by its ability to soak up bumps and dips in the road. This ability is measured in different ways:
The tyre is the component that transmits guidance force to the ground. It is also the first component to transmit vertical movement and vibrations from the road.
vertical wheel-body damping:
The suspension manages the vertical force between the wheel and the body. With its active suspension and electronically controlled springing and damping, the C6 optimises both body control and vertical comfort.
Longitudinal/lateral wheel-body damping:
This damping function is performed by the front and rear suspension. These sub-systems also control the wheel position and thus contribute to on-road behaviour, driving pleasure and active safety. The C6 is the first car to combine hydraulic suspension with double wishbones, a linked hub carrier and a filtered subframe at the front, and a multi-link set-up at the rear.
The seat is the last stage of damping between the road and the passengers. On the C6, the front and rear seats are designed to optimise damping and minimise the vibrations transmitted from the body to the passengers.
Exemplary damping and suspension control
To effectively separate the steering and damping functions on the C6, the suspension features double wishbones with a linked hub carrier at the front, and a multi-link set-up at the rear. As a result, the C6 boasts impeccable road manners in all circumstances, even on uneven, bumpy roads. This virtually eliminates steering vibration while optimising cornering precision.
The double wishbone front suspension transmits lateral force from the wheels to the body, without creating radial force in the suspension. This solution provides far better guidance than a conventional McPherson type set-up. Separating radial and vertical forces thus improves both guidance and comfort.
The vertical and longitudinal stiffness of the subframe mountings which influence driving comfort and road noise, have been disassociated from the lateral stiffness required for good roadholding. The mountings are thus flexible in the directions that control damping and stiff in the directions that control vehicle steering.
The multi-link rear suspension features a longitudinal arm linked to the hub carrier to ensure longitudinal control and to avoid creating vibrations.
The suspension is assembled on a light alloy cross-member to provide good geometrical precision and rigorous dynamic positioning of each wheel, ensuring a precise steering.
More specifically, the architecture of the multi-link rear suspension provides greater latitude in suspension tuning (coupling between the wheel position and vertical suspension travel) and elasto-kinematics (affecting the wheel position on application of longitudinal or lateral force) than a trailing arm set-up. For example, having flexible bushes on the lower link at the front and stiff bushes on the lower link at the rear induces slight toe-in or toe-out when lateral force is applied, thus greatly improving the stability of the rear suspension under load.
The rear suspension bushes of the C6 also play a role in separating the damping and steering functions.
The radial stiffness of these bushes helps to transmit lateral forces and to maintain the wheel position during cornering. When the suspension moves, the mounts are twisted. The more flexible they are, the less stiffness they create in vertical movement of the wheel. Separating the radial and torsional characteristics of the bushes thus provides improved comfort and roadholding.
The C6 suspension bushes take advantage of the intrinsic characteristics of rubber, a material whose stiffness varies depending on the frequency and severity of the loads to which it is submitted.
The hydro-elastic mounts located under the rear axle cross-member serve to filter and adjust vibration frequencies.
Intelligent suspension: active suspension with electronically controlled springing and damping
Continuing a long line of executive Citroën models, the C6 features hydraulic suspension with self-levelling, thus allowing good suspension flexibility for optimum comfort.
The suspension relies on cylinders that transmit the suspension load to nitrogen-filled spheres that play the role of air cushions (or springs in a conventional system) to provide support for the vehicle. Dampers limit body movement by restricting the quantity of oil flowing between the cylinders and the spheres.
Vehicle height is managed by wheel movement sensors. Pressure sensors calculate the load on each axle, and the electric pump (integrated with the built-in hydraulic interface) generates the pressure necessary to raise the vehicle to the correct height.
Each cylinder is linked to a wheel sphere as well as to one or two central spheres depending on the axle. These spheres can be isolated by means of a solenoid.
The suspension of the C6 thus features two stiffness settings, as on the C5. The choice will depend on road characteristics and driver input.
This highly flexible and comfortable suspension system changes to a firmer setting to optimize body control during cornering, acceleration or braking. It is a system that combines comfort with exceptional roadholding.
To further increase the efficiency of the suspension system with its new multi-link rear suspension, the C6 gains a second central sphere on the rear axle, thus making sure that passengers at the back enjoy the same high standards of comfort as passengers at the front.
Additionally, the two hydraulic suspension settings are complemented by 16 variable damping settings that are managed independently for the four wheels. Damping control settings are switched at high speed (in 2.5 ms, or up to 400 times per second), thus allowing the system to control the load on each wheel in real time by altering damping control during vertical movement of the suspension. The system can thus effectively soak up bumps or dips in the road surface.
The suspension control system collects all the information relating to the state of the road and driver input: movement and speed of vertical movement of each wheel, vehicle load, vehicle speed, engine torque, braking pressure, lateral acceleration, steering wheel angle, etc. Through this information, the system is able to "read" the road, adapting to its characteristics and to driver input in order to improve comfort and body control.
The suspension control unit has two operating modes: “SkyHook” and “RoadHook”.
SkyHook, the main operating mode, places the emphasis on comfort and body control. Using the above data and a model of vehicle suspension, it reconstitutes vehicle movement with reference to a fixed point (the sky), rather than a moving point such as the road.
The system calculates the damping force to be generated to simulate a vehicle whose dampers are linked not to the road but to a point at a constant height that is moving with the car. Using this artificial calculation, the system applies the real-time damping force necessary to minimise body movement in relation to the fixed point and thus in relation to the sky, hence the name of SkyHook.
As a result, passengers have the impression of a "magic carpet" ride.
When the driver adopts a sportier driving style, a second operating mode called RoadHook kicks in. This mode places the emphasis on road holding. The objective here is to apply to each wheel the force necessary to adapt to the characteristics of the road. The switch from SkyHook to RoadHook depends on input from the driver during acceleration or braking. After these transitions, the hydropneumatic suspension will have switched to a stiff setting and damping control is adjusted for each of the four wheels.
The suspension of the C6 features a "sport" position. This allows the driver to choose a more dynamic driving style for sporting sensations.
Some specific situations are processed by special programs in order to make full use of the suspension’s potential.
An "impact" program detects major obstacles encountered by the front wheels (potholes, speed bumps, etc.) and instantly switches to a higher damping control setting to soak up the vibrations. The system calculates the time elapsing before the rear wheels go over the same obstacle, based on the vehicle’s current speed. Damping is thus reduced in order to better soak up the obstacle and limit the effect felt by the passengers.
A "wheel bounce" program detects bouncing of the wheels on poor surfaces (speed bumps, …) that adversely effect wheel-road contact and – in consequence – vehicle behaviour, stopping distances and vibration control. This module makes it possible to increase damping only in these cases, without affecting comfort in other situations. This ensures perfect damping whenever necessary.
This suspension maintains the vehicle at a constant ride height, regardless of the vehicle load and number of passengers and to insure this, body height is monitored in real time.
In specified conditions, this system can automatically lower the vehicle by around a dozen millimetres from 110 kph, thus optimising high-speed steering as well as fuel consumption.
This suspension requires no maintenance for five years or 200,000 km.
Safety and Equipment
An advanced-safety braking system
The C6’s high-performance braking system features four ventilated discs, measuring 330 mm in diameter at the front, and 302 mm at the rear.
With the dedicated braking assistance / control functions and ESP, the driver is able to maintain control and keep the car on course even in the most difficult driving situations.
In terms of passive safety, the C6 features efficient restraint systems for all the occupants, together with a structure designed to resist the most violent impacts.
Nine airbags including one for the knees
The deployment pressure and volume of the two front airbags depend on the severity of impact.
A knee airbag provides improved protection for the driver’s knees and shins by limiting impact with the steering column, which retracts by 80 mm.
Seat-integrated side airbags at front and rear protect the chest and abdomen of the passengers in the event of side impact. The C6 is also fitted with curtain airbags providing head protection for passengers at the front and rear.
Active headrests on the front seats prevent whiplash injuries in the event of rear impact. The force generated by the passengers’ upper bodies pressing against the seat backs activates a lever system that moves the headrests forward to cradle the occupant’s head, and thus avoid strain on the neck.
The body structure
The C6 features the passive safety functions of platform 3 vehicles, inaugurated with the C5.
This platform base sets high standards in driver and passenger protection, as illustrated by the C5’s results in EuroNCAP tests.
The body has high torsional rigidity of 0.77 mrd for torque of 100 Nm. This rigidity makes full use of the running gear for enhanced road manners.
The C6 features two impact absorbers at the front.
Two-thirds of the energy from the impact is taken by the upper absorber and one-third by the lower. This guarantees the stiffness necessary for protection in the event of high-speed frontal impact, and the flexibility needed to absorb impact at lower speeds.
A system attaching the engine to the cradle completes the protection against high-speed frontal impact by limiting how far the powerplant can move backwards into the passenger compartment.
Finally, the body frame and the superstructure are designed to absorb the energy from side impact and maintain a survival cell for the passengers.
In addition, a “pedestrian” cross-beam fitted with shock absorbers ensures the protection of pedestrians in the event of minor impact. This feature works with the active bonnet system.
Active bonnet system
The powertrain generally takes up considerable space in the engine compartment, leaving little room between the engine and the bonnet.
To remedy this, the C6 comes with an “active” bonnet system as standard that automatically raises the bonnet in the event of pedestrian impact. Thanks to an impact sensor and pyrotechnic mechanism, the bonnet rises 65 mm in 40 milliseconds. A second mechanism maintains the bonnet in its raised position despite the impact and thus absorbs impact energy.
A head-up display for ergonomics and safety
Always an innovator, Citroën is bringing customers a system that remains rare in the automotive market: a head-up display. Adjustable for height and brightness, the display projects key driving information – such as speed and navigation data – onto the windscreen in the driver’s direct line of vision.
The head-up display makes a significant contribution to safety with its direct read-out. Drivers assimilate data more quickly and do not have to look away from the road.
A total 0.5 seconds are saved, based on the time taken by drivers to look away from the road and adapt their vision.
The virtual image is produced by a projection unit in the dashboard, which creates a remote display through the windscreen.
The driver can decide which information to display, from a list of possible items. Vehicle speed is visible continuously when the system is running.
Dedicated controls are placed on the fascia band, near the wheel. The driver can switch the display on or off, adjust image height and brightness and select the information required.
The head-up display is fitted with a brightness sensor to maximise the visibility of information, whatever the level of exterior brightness.
Electric parking brake
The C6 features an electric parking brake, This system automatically adjusts the tightening torque necessary to immobilise the car. Ergonomic controls are provided on the central console.
The electric brake is used in the same way as a conventional handbrake.
Speed-sensitive air deflector
A speed-sensitive air defector on the tailgate deploys automatically to enhance vehicle aerodynamics and high-speed stability.
The deflector has three possible positions, depending on vehicle speed. Deploying from 65 kph, it takes on an increased angle from 125 kph, returning to an intermediate position for speeds of below 105 kph and to its initial position at under 25 kph.
Lane departure warning system (LDWS)
After the C4 and the C5, the C6 is fitted with a LDWS, one of the first systems designed to counter the problem of drowsiness at the wheel.
Once activated, the LDWS detects any unintentional lane changes with indicators off, on a motorway or major road at speeds of 80 kph and over.
A vibrating mechanism mounted in the car seat is activated on the side corresponding to the direction of vehicle drift in order to alert the driver, who can then steer the car back on course.
Xenon dual-function directional headlamps
The C6 can be fitted with electronically controlled xenon dual-function directional headlamps to improve visibility when cornering.
These intelligent headlamps comprise an elliptical bi-xenon directional module, which is active in both the low-beam and high-beam positions to ensure excellent visibility at night or in bad weather. These headlamps let the driver see the road and distinguish other road users and possible obstacles. This is an important advantage in terms of safety since, at a speed of 110 kph, the car covers more than 30 metres every second.
Citroën first introduced this useful innovation on the DS – another great Citroën. At that time, this function – already appreciated for its efficiency – was mechanically controlled. A nod to great Citroëns of the past.
Front and rear parking assistance
Front and rear parking assistance is a driving aid that has become both essential for urban runabouts and for large vehicles such as the C6.
Sensors located in the front and rear bumpers detect any obstacles close to the vehicle. The bleeping loudspeaker and the picture on the multifunction screen tell the driver exactly how close he or she is to the obstacle detected.
Using a rain sensor positioned on the windscreen, this function controls the automatic trigger and wipe rate in line with the intensity of the rain. The driver no longer has to stop and start the wiping function and can therefore concentrate on the road.
The C6 is also the first vehicle in the range to feature new butterfly windscreen wipers.
Two opposed arms controlled by two synchronous motors, describe a butterfly type movement, allowing the blades to cover a wide area of the windscreen. The flat-blade design of the wipers ensures quiet, efficient operation.