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OverviewAppointments and technical highlights of the new C-Class Estate*Body: A model of strength, safety and lightweight designChassis: A blend of agility and comfortDesign: Cast from a single mouldEngines and transmissions: Extra power coupled with far lower fuel consumptionInterior: Taking spaciousness and load capacity into a new dimensionModel range: As multifaceted as daily lifeSafety: Innovations borrowed from the luxury classTechnical dataThe new C-Class Estate: Unrivalled spaciousness, plus exemplary safety, optimum comfort and tangible agility
Sep 11, 2007
- Largest load capacity of all premium-class estates in this market segment
- Load compartment designed for everyday practicality
- Handy details for transporting loads safely and easily
- Newly developed seats with two-zone comfort
- Voice control with whole-word commands for first time
- Automatic climate control up to 15 per cent more efficient
The level of comfort and freedom to move inside the new C-Class Estate match the exemplary standards set by the Saloon - meaning they are a clear improvement on the predecessor model. A body that is 55 millimetres longer and 42 millimetres wider than previously, plus an extra 45 millimetres of wheelbase length create the conditions needed for an even more spacious interior. This is quite evident, for instance, in the greater distance between the front and rear seat reference points, which is now 795 millimetres and therefore exceeds that of the outgoing Estate by ten millimetres. Passengers in the rear now benefit from eleven millimetres more legroom.
The occupants also enjoy more space and comfort thanks to the new interior widths, with both front shoulder room and elbow width increased by 40 mm to 1390 and 1440 millimetres respectively. In the rear, the Estate offers 1398 millimetres of shoulder room and 1462 millimetres of elbow width - an increase of 20 and 40 millimetres respectively compared to before.
Mercedes engineers also attached great importance to comfort when entering and leaving the vehicle. Passengers are now seated seven millimetres higher, which makes getting into the vehicle that little bit easier. Access is further facilitated by the straight front edges of the B-pillars, the larger front door aperture and the new shape of the seat cushions in the rear.
Load capacity: new benchmark figure in this estate class
Versatility and individuality - these attributes of the new C-Class Estate are most obvious when considering its rear compartment. The seat unit plays a key role here on account of its backrest which splits asymmetrically - in the ratio 1/3 : 2/3 - opening up many different possibilities for arranging the interior individually as desired. In this way, drivers can transform the Estate from a five-seater into a four, three or two-seater by folding either or both of the seat backrest sections flat. And doing so could not be easier, as both can be folded forwards in a single action. The result is a virtually flat load floor measuring around 1.80 metres long and up to 1.20 metres wide.
Luggage capacity is 485 litres, or 690 litres when filled up to roof level, and load space can be increased to a total of 1500 litres (loaded to roof level, VDA measuring method) by folding the rear backrests flat, providing a clear indication of just how cavernous the new C-Class Estate is inside. No other model in this premium estate class has so much room on offer. Compared to its predecessor, the new Estate is able to accommodate as much as 146 litres more, an improvement of over ten per cent.
The table below shows how the interior of the new Mercedes Estate "grows" with the tasks expected of it:
However, the designers of the Estate were less concerned with the somewhat theoretical measurements produced by the standardised VDA method, preferring to focus instead on the loading situations encountered in everyday life. The Mercedes design engineers wanted to find out what actually fits into the Estate -- from a pram to domestic appliances, from a set of luggage to packing cases. Meaning that the car was developed under real-life conditions. A computer simulation enabled the new Estate to be taken on digital "shopping trips" long before the first driveable prototypes were ready. A basket of commodities containing hundreds of different items was stored on the computer and could basically be loaded at the click of a mouse. This approach allowed the engineers to instantly determine what fitted into the load compartment or see where things were a little tight. Real tests conducted with the first prototypes of the Estate months later corroborated the findings of the digital development work and confirmed the new model's tremendous versatility.
The measure of all things for estate car enthusiasts - as the experts at Mercedes know perfectly well - is the size of the largest possible cuboid that fits into the load compartment when the rear backrest is completely folded down. The dimensions of this cuboid say a great deal about an estate's day-to-day practicality as they are a gauge of its ability to transport bulky objects. The largest cuboid that can be fitted into the new C-Class Estate measures 943 x 599 x 1465 millimetres. This equates to a volume of 827 litres, 66 litres more than on the outgoing model and between 50 and 100 litres more than other comparable premium estate models.
In practical terms, the large dimensions of this cuboid mean that the new Mercedes Estate is spacious enough to fit in, for example, a washing machine, a refrigerator, a large TV screen in its original packaging, a two-seater sofa, chests of drawers or sideboards. Garden loungers or four golf bags plus trolleys can likewise be comfortably accommodated by the load compartment.
Yet another class-beating value is the maximum utilisable interior length of 2.82 metres, measured from the tailgate to the front passenger footwell. That is a whole 17 centimetres more than in its predecessor.
But anyone intending to go on holiday with their whole family plus luggage, or move or embark on a major shopping trip, needs more than just a roomy, flexible car; they need a car with a high payload capacity too. Here, once again, the new C‑Class proves itself to be more than up to the task, with a maximum DIN payload of 605 kilograms.
Load management: EASY-PACK for safer, more convenient transportation
Apart from spaciousness and good versatility, functionality also came high on the list of priorities for development of the new C-Class Estate. The objective was to make loading the Estate easier, safer and more convenient with an array of practical details. Take the EASY-PACK power tailgate (optional) for instance: a mere touch of a button on the Estate's electronic ignition key and an electromechanical drive swings the tailgate upwards, far enough for an adult to stand upright beneath it. Closing the tailgate again is just as straightforward, and is triggered by simply pressing either the red pushbutton on the tailgate's interior trim or the switch in the driver's door. The maximum opening angle can furthermore be programmed to prevent the tailgate from knocking against the garage roof. The coat hooks incorporated into the interior trim come in particularly handy for anyone who plays sport or goes rambling in their free time, as they are able to hang up their jackets whilst changing under the open tailgate.
Yet another feature testifying to the Mercedes engineers' impressive attention to detail are the load hooks in the load compartment's sidewall trim -- when pressed lightly they extend outwards, providing an ideal support for holding handbags or bags of shopping. As on all estate models from Mercedes-Benz, the standard specification comprises an extending dividing net combined with a retractable cover to protect the load compartment from prying eyes.
Underneath the sturdy load compartment floor, the Estate car conceals another large stowage compartment in the form of the spare wheel well. This is the home of the standard shopping crate, which can be securely stowed under the load compartment floor not only when it is folded flat but when it is in use too. Despite its name the spare wheel well is usually empty, as the C-Class Estate leaves the factory complete with the practical TIREFIT tyre sealant as standard.
The Estate's facilities for secure, intelligent loading can be extended by opting for the EASY-PACK load-securing kit. Aluminium rails along both sides of the load compartment floor serve as a basis for ...
- ... four movable load-securing rings which are attached directly to the aluminium rails;
- ... a telescopic bar whose bases can be locked into the load-securing rings. The telescopic bar enables the load compartment to be divided crossways and diagonally;
- ... a retractable belt with a broad fabric strap which locks into the load-securing rings. It can likewise be used to divide the load compartment crossways or diagonally, whereby the flexible strap can also be routed around objects to prevent them from sliding.
The equipment details for transporting loads safely and easily at a glance:
· Combined luggage cover and retaining net
· Load-securing rings (x4) in load compartment floor
· Bag hooks (x2) in load compartment
· Coat hooks on the inside of the tailgate
· Stowage compartments (x2) with net fronts in load compartment
· Collapsible shopping crate
· EASY-PACK tailgate with electromechanical drive
· EASY-PACK system with load-securing rings, telescopic bar and retractable belt
Seats: long-distance comfort as standard
Because the seats can make a major contribution to comfort on long journeys, the Mercedes engineers took particularly great care over their design. The result is newly developed front seats which offer further benefits in terms of pressure distribution and lateral support. This was made possible by developing a seat contour with more prominent side seat bolsters and by the use of two-zone seat padding: in the outer areas – and especially in the bolster cushions - the foam padding is rather firmer to offer good lateral support, while the inner area of the seat cushion has deliberately been made softer.
In addition, the foam padding on the seat cushion has been made around five per cent thicker than in the preceding model. In this way the Mercedes specialists have achieved a uniform pressure distribution and avoided pressure peaks - especially in the area underneath the pelvic girdle - which can cause discomfort during a long journey.
The foam seat padding is supported by seat shells with integral springs. A frame made partly of high-strength steel provides a firm base for the front seats. Special tubular sections and impact-absorbing elements in the seat trim ensure that the seats are able to absorb high impact forces in a side-on collision and transfer them to the other side of the vehicle. The backrests of the front seats consist of a steel frame and foam pads whose contours, like those of the cushions, have also been designed for better lateral support. The volume of the foam backrest has been increased by around five percent compared to the outgoing model. With the aid of the lumbar support included as standard, the driver is able to adjust the backrest contour to his spinal anatomy, thereby relieving the strain on the back muscles - a further contribution to long-distance comfort.
As before, the height and backrest angle of the front seats are electrically adjustable, while the fore-and-aft position and seat cushion angle are adjusted manually. At 290 millimetres, the new C-Class Estate boasts the longest longitudinal seat travel in this market segment. The individual seat position can be adjusted in very small increments of just 4.5 millimetres, meaning it is virtually infinitely variable. The backrest angle is smoothly adjustable too. As a result, both very tall and very short drivers are able to find a seat position that puts all the vehicle controls within easy reach. The adjustment ranges of the front seats are as follows:
- Fore-and-aft adjustment 290 millimetres
- Seat height 54 millimetres
- Seat cushion angle 4.8 degrees
- Head restraint height 85 millimetres
Even more operating convenience is provided by the fully electrically adjustable front seats that can be ordered as an optional extra. In this case, electric motors adjust not only the seat height and backrest angle, but also the fore-and-aft position, seat cushion angle, head restraint, steering column as well as the exterior mirrors. If the memory package is specified, three individual settings can be stored – simply pressing a button on the door panel causes the seats, steering wheel and exterior mirrors to move into the corresponding pre-programmed position automatically.
Multicontour seat: air cushions for adaptability
The multicontour seat is a well-proven Mercedes invention that greatly contributes to the long-distance comfort of passenger cars bearing the star. Multicontour means that the occupants are able to adapt the contours of the seat to suit their anatomy or personal preferences. This is made possible by separately controllable air chambers beneath the seat padding.
Mercedes-Benz offers an advanced version of the multicontour seat as an optional extra for the C-Class. The new technology monitors the selected contour settings and ensures that the pressure in the air chambers remains constant at all times. Two of these chambers are located in the backrest, where they act as a continuously variable lumbar support; the seat side bolsters also include one air chamber each, while another inflatable air cushion is used to adjust the seat cushion length.
Sports seats with more pronounced cushion and backrest side bolsters affording sportier lateral support are available for the driver and front passenger in conjunction with the AMG sports package.
Rear seats: comfortable, versatile and safe
The rear seat unit with its further improved foam cushion is of one-piece construction as standard. Three head restraints and three inertia-reel seat belts ensure the safety of the occupants. The outer rear seats are also equipped with belt tensioners and belt force limiters, as well as head restraints that are adjustable for height and angle. ISOFIX, the standardised attachment system for child seats, is included as part of the rear seat unit too. As an option, Mercedes-Benz can equip the C-Class with integrated child seats which fold out of the rear bench seat cushion at the push of a button, and now also offer the benefit of a wraparound head restraint.
The rear seat unit features a centre armrest with an integral stowage compartment and cup holder for two cans or beakers as standard.
Dashboard: harmony of high-tech and stylish looks
"What looks good must also feel good" – this is the Mercedes principle applied by the dashboard, centre console and the transmission tunnel and door trim in the new C-Class. This is because the experts in Sindelfingen regard pleasant tactile qualities and high-class looks as making a major contribution to comfort and wellbeing.
The dashboard may be ordered with a two-tone colour scheme as an option, in which case a darker colour is used for the upper section and centre console, while the knee bolster, glove compartment lid and tunnel console stand out with their lighter, contrasting finish. The instrument cluster, controls and air vents are a perfect fit, and blend harmoniously into the styling concept. Precision edges and tight radii set set the tone for the high-quality appearance. The illuminated glove compartment has a capacity of 6.4 litres and can be cooled by the air conditioning system. It also accommodates a twelve-volt power socket and a jack for connecting an external audio device (if a radio is fitted).
An aluminium cross member acts as a robust support for the dashboard and its components. The glove compartment, airbag, centre console and jacket tube are attached to this solid section, which is around 1.8 kilograms lighter than a comparable welded steel construction. The cross member reduces resonances and vibrations, and helps to give lateral support to the A-pillars to which it is bolted at both ends.
The centre console is harmoniously integrated into the dashboard's design and colour concept. The controls for the audio system and telephone (optional) are positioned below the air vents. A clearly defined edge delineates this area from the lower middle section of the dashboard, which houses the control unit for the standard air conditioning system. This is followed by an almost right-angled transition to the tunnel console, in which the shift lever, the controller and an asymmetrically divided armrest are to be found. On the driver’s side this armrest extends well forward, serving as a practical handrest for operation of the controller. Beneath it is a spacious stowage compartment.
If the new Estate is equipped with THERMOTRONIC three-zone luxury automatic climate control, the tunnel console also features a blower along with a separate control panel for passengers in the rear.
The switches, buttons and controls have been arranged in line with the latest ergonomic findings, and are positioned based on either the importance of their functions, their frequency of use or visual considerations. This means that the uppermost position in the centre console is occupied by the prominent red button for the hazard warning lamps, where it can be accessed just as easily by both the driver and the front passenger. This is followed by a strip of switches featuring controls for optional equipment, such as heated seats or PARKTRONIC; the lower end of the centre console is formed by the control panel for the automatic climate control.
Cockpit: precise information at a glance
The round dials with their chrome bezels, black faces and white markings are illuminated in white and lie in the driver’s primary field of vision to provide information on the vehicle speed (centre) and engine speed (right). The gauges for coolant temperature and fuel level, meanwhile, are located in the left-hand cylinder of the instrument cluster. The use of black-panel technology means that the warning and indicator lamps are not visible during normal operation – they can only ever be seen when the ignition is switched on or in the event of a fault.
In addition, each dial incorporates a display as standard, indicating e.g. the time (left), total and trip mileage, plus any warning messages (centre), and the outside temperature (right). The display functions can be selected using the four buttons on the standard multifunction steering wheel.
In the ELEGANCE and AVANTGARDE lines, the instrument cluster is linked to a luxury multifunction steering wheel and offers even more functions. In the centre of the speedometer there is a white backlit, two-section 4.5-inch central display whose upper section can be used to show a variety of information such as the odometer reading, range, oil level, distance and time travelled, average fuel consumption and average speed. If a navigation system (optional) is installed, this display area also indicates the route for the current journey. This display is furthermore used to select the radio station, telephone numbers and up to 50 individual settings.
In addition to various pictograms, the lower section of the central display shows the time, outside temperature, current gear and gearshift mode (on automatic models) and vehicle speed in digital form.
Control concept: everything in just the right place
The control and display concept of the new C-Class is a logical and intelligent evolution of the successful control system familiar from the luxury CL and S-Class Mercedes models. It is rooted in the understanding that any technology can only be perfect if its operation can be understood and mastered intuitively. The Mercedes engineers were guided by four basic principles:
1. Easy identification of the most important control functions
2. Rapid access to the most important spontaneous functions
3. Easy, intuitive operation of the most important functions
4. All controls located in the right place
Rapid access to frequently used functions is a key characteristic of the control concept in the new C-Class. This means that the driver is not required to relearn, is able to retain old habits and immediately feels at home. All the important control and display elements necessary during a journey are located in the cockpit, i.e. in the driver's immediate proximity. These include, for example, the switches and control stalks for the vehicle lights, wipers, indicators and cruise control (standard on automatic models). In the same way, linking the standard multifunction steering wheel with the instrument cluster is the perfect way of providing rapid access to a multitude of information and functions which appear directly in the driver’s field of vision.
Other functions such as infotainment, which are not of primary importance to the driver, appear in a display in the centre of the dashboard. The driver and front passenger are able to operate these functions using the controller on the centre console, or access the main menus by means of direct selection keys.
Following the "everything in the right place" principle, functions such as the power windows, central locking system and exterior mirrors are controlled from where one would expect to find the relevant switches and buttons, namely on the doors.
Steering wheel: a command centre with a dozen buttons
To allow rapid selection of these settings and functions, Mercedes-Benz has further developed the controls on the standard multifunction steering wheel: in ELEGANCE and AVANTGARDE models the steering wheel has twelve circular, illuminated buttons which the driver operates by light thumb pressure. Using the left-hand disc, the driver can highlight one of the main menus in the central display in a horizontal direction, then access the required submenu vertically. The relevant selection or setting is confirmed by pressing the "OK" key in the centre of the button. A separate "Return" button enables the driver to quickly return to the next menu level up.
The buttons on the right-hand side of the multifunction steering wheel are used to adjust the volume setting (vertical), switch to mute (centre) and operate the car phone (horizontal). Below this there is an additional button with which the driver can activate the LINGUATRONIC voice control system (standard with COMAND APS and Audio 50 APS combined with six-disc DVD-changer).
Controller: rotate, press and nudge
The controller positioned on the tunnel console is standard equipment if the new Estate is ordered with a factory-fitted radio or navigation system. It is linked to the clearly laid-out colour display in the centre of the dashboard, which is positioned far forward to be well within the driver’s field of vision. The turn/push selector is made of aluminium and can be moved in any direction: rotating the controller selects the main and sub-menus in the display, pressing it confirms the relevant function. The buttons in front of the controller make it possible to quit the submenus immediately or delete entries.
As the operating system for the infotainment units has a duplicate design, the radio, CD/DVD changer, telephone and navigation system can be accessed both via the controller and by pressing control buttons. The latter are function keys in the centre console, whose ideal ergonomic positioning allows drivers to operate them easily without diverting their eyes from the road.
Infotainment: choice of three top-class units
Three optional, high-performance units are available to provide infotainment to the occupants of the C-Class. All of these include speed-sensitive volume control, a keypad for entering telephone numbers and radio frequencies, as well as a Bluetooth interface for wireless connection of mobile phones to the hands-free system:
- Audio 20 with CD player and 80-watt amplifier
This car radio with built-in CD player (MP3-capable) includes an FM/MW/SW and LW tuner with automatic station search, RDS (for FM reception), direct frequency input via the keypad in the centre console, a 4x20-watt amplifier and eight loudspeakers. The Audio 20 unit is linked to a fixed, 4.9-inch colour display located in the centre of the dashboard, where it is well within the driver’s field of vision and can disappear out of sight beneath a cover whenever required; it continues to operate even when the cover is closed. The unit is optionally available with an integral six-disc CD changer, in which case it may also be combined with the surround-sound system.
- Audio 50 APS with optional voice control
This infotainment system combines a car radio, telephone switchboard and Europe-wide DVD navigation system into a single unit. The route guidance information - sometimes including attractive junction zoom graphics - appears in the form of arrows on the fixed, 4.9-inch colour display in the dashboard, which can be covered whenever required without interrupting the operation of the unit. The radio functions are the same as those of the Audio 20 unit. The built-in DVD player is able to read both navigation and audio data, while an integral six-disc DVD changer is available on request. This variant also includes the advanced version of the LINGUATRONIC voice control system with whole-word commands.
- COMAND APS with hard drive for navigation and music server
The COMAND APS multimedia system developed by Mercedes-Benz offers even more functions than before in the new C-Class. One new feature is a Europe-wide navigation system whose data is stored on a 30-gigabyte hard disc. This allows extra-fast access to the navigation data, with even faster route calculation compared to DVD navigation. The high-resolution maps are shown on a 7-inch colour display, which tilts away and disappears beneath a cover at the touch of a button. During route guidance, the navigation system also makes lane recommendations to allow drivers to select the most appropriate lane at motorway junctions, for example. A junction zoom display allows a more realistic graphic representation of road junctions. For the first time, COMAND APS also includes a music server with a 4-gigabyte memory. This enables the driver to store up to 1000 tracks from a CD, DVD or memory card. Music tracks are recognised by the system automatically and shown in the colour display. A DVD player for video and audio is also included, and an integral six-disc DVD changer may be specified as an optional extra. Below the DVD unit is a PCMCIA slot which enables various PC memory cards to be connected and the music files they contain reproduced. Mercedes-Benz combines COMAND APS with the LINGUATRONIC voice control system as standard. Otherwise the radio, amplifier and speaker specification is identical to that of the Audio 50 APS unit.
As an option, passengers in the new C-Class Estate are able to enjoy an audio experience of such high quality that it is like being at a live concert. It is all made possible by the "Logic7" surround-sound system, which Mercedes-Benz developed together with the audio specialists harman/kardon® and which celebrated its world debut in the S-Class in 2005. Based on technology never before seen in a car, this system delivers three-dimensional sound as a natural 360-degree musical experience for all passengers, from both DVD and CD and regardless of whether the source was recorded in 5.1 surround or normal stereo. The audio signals are distributed via a 450-watt amplifier connected to eleven speakers plus a bass box in the load compartment's side trim.
Voice control: as many as 220,000 street names stored
Scientists have been working on the development of computer-based speech recognition for over two decades now. In 1996, Mercedes-Benz became the very first automotive brand to offer such a system in its cars: LINGUATRONIC. Since those early days, Mercedes speech-recognition technology has progressed in leaps and bounds. The very first generation of the system only required 512 kilobytes of computer memory - today, the system takes up over ten megabytes.
With the arrival of the new C-Class, LINGUATRONIC has attained its most advanced state of development: quite apart from operating the telephone as well as the audio and navigation systems, the voice-control system is now capable of understanding whole-word commands when inputting a destination, selecting a radio station or making a phone call. This means that instead of having to spell out place names and streets, drivers simply have to say where they would like to go.
During the brief dialogue between driver and LINGUATRONIC, the sound signal is digitised, transformed into a frequency spectrum and then analysed. During this process, the computer extracts certain features from the sound signal at lightning speed. Doing so allows it to recognise the phonemes, which are the acoustic building blocks of any given language. By combining the phonemes and cross-referencing them with the contents of the phonemic dictionary stored in the system, the voice control can recognise whole words. Every language has its own set of characteristic phonemes -- around 40 are used by LINGUATRONIC for the German language. In all, the phonemes for six different languages have been loaded into the system, allowing it to recognise not just German but English, French, Italian, Spanish and Dutch too.
The voice control system processes the sound units - the phonemes - as digital codes. The electronics analyse each sound, join the different phonemes together, and finally also check the acoustic plausibility of the word, all in a matter of milliseconds. In this way, the system is even able to recognise the finest nuances in pronunciation, meaning that it can distinguish, for example, between the words "town" and "down".
However, it is not the LINGUATRONIC system's ability to understand every word that is crucial so much as its ability to understand every driver. Everyone has a distinctive pronunciation, and speaks at their own pitch and speed. In order to make allowance for these individual characteristics, the system was subjected to an exhaustive learning process. Over the course of its development, it was checked in all languages and tested by motorists from all the different regions where a particular language was spoken.
The largest active vocabulary boasted by the LINGUATRONIC system for the C‑Class can be found in the US state of California, where some 220,000 street names can be inputted directly as whole words.
Mercedes-Benz makes an important contribution to traffic safety too with LINGUATRONIC, as drivers no longer need to take their hands off the wheel to operate the car phone or the audio units. In this way, LINGUATRONIC lessens the driver's workload, making it easier to concentrate on what's happening on the road ahead. In the new C-Class, Mercedes-Benz also uses voice synthesis to provide the driver with important traffic information affecting the planned route or to read out SMS text messages.
The new improved LINGUATRONIC system is included as standard on C-Class models which leave the factory equipped with either Audio 50 APS and the six-disc DVD changer or with COMAND APS.
Climate control: three-zone comfort as a first in this model class
The new C-Class Estate has also made significant advances over the preceding model where climate control is concerned. The engineers in Sindelfingen have developed two air conditioning systems, one of which - THERMATIC - is fitted as standard in the Estate. The optional THERMOTRONIC system permits three-zone climate control in the interior, something which no other vehicle in this model class is able to offer at the current time.
In terms of both heating and cooling output, these two air conditioning systems achieve even better performance than before:
- The heating output has increased by around ten per cent to eleven kilowatts, thereby matching the capacity of the central heating system in a modern family home. In the diesel models, a heat exchanger with six integral PTC heating elements (Positive Temperature Coefficient) cuts in to boost the effect of the main heat exchanger, depending on the outside temperature. The assistance from this PTC heater is necessary due to the high thermal efficiency of today’s CDI engines, which is precisely what makes them so economical and means they release considerably less heat to the coolant under partial load conditions than other engines.
- The air conditioning system's cooling output has been increased by between 10 and 15 per cent. The refrigerant compressor is continuously variable, which allows the air conditioning system to be operated in accordance with requirements, i.e. economically. A solenoid valve controls this adjustment process by varying the displacement of the refrigerant compressor.
- Revised flow areas for the air intake, air ducts and air conditioning unit have enabled the noise level to be reduced by around three decibels (dB(A)).
Another important comfort feature is the prevention of draughts. To this end, Mercedes engineers have further enlarged the cross-sections of the air vents to reduce the speed of the airflow - and therefore the risk of irritating draughts. The task of effective, uniform ventilation of the interior is taken care of by a total of 16 air outlets. With the exception of the defroster vents below the windscreen and the air outlets in the footwells, the quantity of air passing through each individual air vent is infinitely adjustable. The THERMOTRONIC system also features an automatically controlled, upward-pointing diffuser nozzle in the dashboard, which provides indirect and therefore draught-free ventilation.
A sophisticated system of sensors ensure that the preferred temperatures selected by the occupants remain constant. Two sensors measure the relevant interior temperature and provide the system with even more precise data, allowing it to respond to temperature fluctuations more rapidly. In addition, four sensors monitor the temperature of the air flowing from the air vents and allow a continuous target vs. actual comparison to be made. Another sensor registers the intensity and direction of the sun's rays. Using this data, the automatic climate control system can adjust the flow rate and temperature of the air according to the driving situation or weather conditions, and ensure that the occupants of the C-Class are able to enjoy a consistently high level of climatic comfort.
The sensors in the THERMOTRONIC system are supplemented with a dewpoint sensor and a pollutant sensor. Thanks to the dewpoint sensor the inflowing air can be cooled and warmed up again if required, depending on its moisture content. This makes the air conditioning system all the more economical. The pollutant sensor detects excessively high levels of carbon monoxide and nitrogen oxides in the outside air, automatically switching to air recirculation mode if concentrations of these pollutants suddenly increase.
A large, hermetically sealed combination filter which forms part of the standard specification also purifies the air before it reaches the vehicle interior. This filter retains 100 per cent of all particles larger than ten micrometers, while absorbing unpleasant odours thanks to its activated charcoal lining. It is permanently active, even in air recirculation mode. The practical tunnel setting is another technical feature of THERMATIC and THERMOTRONIC: if the driver or front passenger presses the air recirculation button on the air conditioning control panel for longer than two seconds, all open side windows and the sliding sunroof close automatically. If the button is then pressed and held for some time again, the windows and sunroof reopen to the same position as before.