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Press Information

29 November 2010


MATIC: the intelligent all-wheel drive system

Contents

Page





The tenth all-wheel drive model series from the pioneer

4MATIC permanent all-wheel drive for the CLS for the first time



2







The automatic drive for wintry road conditions

Sure, predictable handling, plus impressive driving dynamics



7







The current 4MATIC generation

Lighter, more compact, more efficient



11







Four bestsellers involved in winter test

Exceptional traction combined with varying characters



13







At a glance

The full range of all-wheel drive passenger cars from Mercedes-Benz



19







History: the story of the all-wheel drive models from Mercedes-Benz

Over 100 years of traction to the power of four



22

The descriptions and information in this press kit apply to the international Mercedes-Benz model range and may vary from country to country.



The tenth all-wheel drive model series from the pioneer

4MATIC permanent all-wheel drive for the CLS for the first time



Stuttgart/Hochgurgl – For years now, Mercedes-Benz has been successful as a 4x4 manufacturer in the premium segment. Production has soared since the launch of the M-Class in 1997. Today, Mercedes-Benz offers nearly 50 models with 4MATIC across ten model series.

One of the fundamental factors in its success is the formidable performance of the 4MATIC drive concept on snow-covered or icy roads, with its high traction reserves, excellent directional stability, peerless safety and exceptional
comfort levels.


The new CLS is capitalising on these benefits too. For the first time, the four-door coupé is available with all-wheel drive in the guise of the CLS 350 CDI 4MATIC BlueEFFICIENCY and CLS 500 4MATIC BlueEFFICIENCY.
Besides the CLS, the 4MATIC Workshop being staged in extreme winter
conditions on the Timmelsjoch high alpine road in Austria also features
the current versions of the S-, CL- and R-Class.

As with the 4MATIC system's set-up on a dry or wet road, directional stability and, therefore, active safety are paramount at all times when wintry conditions prevail, too. The mechanical principle of the 4MATIC system featuring a


45:55 torque split between the front and rear axles and the multi-disc limited-
slip centre differential with a basic locking torque of 50 Nm offer all the right ingredients. This basic design enables high levels of traction, as the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. However, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving on the limit: in such instances, a yellow warning symbol flashes in the instrument cluster as a highly visible prompt to adapt their driving style to the road conditions.

The drive mechanism's permanently engaged design offers key advantages over other systems that first need to diagnose a lack of grip before activating the


all-wheel drive. The 4MATIC system on Mercedes-Benz models will have already made use of this valuable time to start transmitting drive torque via the wheels to the road.

4MATIC: stable handling on snow and ice

When pulling away in wintry conditions, the 4MATIC models are designed to develop maximum traction. To this end, certain road conditions are automatically detected and the interventions of the 4ETS electronic traction control system


adjusted so as to achieve the greatest possible acceleration while minimising wheel slip, ensuring optimum directional stability in the process. This strategy also allows the vehicle to pull away under the most adverse conditions, such as when one side of the vehicle is on an icy slope (µ-split) or both wheels on either the front or rear axle have limited grip (µ-jump).

On twisting roads covered with snow and ice, vehicle stability is primarily


controlled by the ASR acceleration skid control system's regulation of engine torque. The ASR control thresholds are adjusted according to the driving situation based on the vehicle's longitudinal and lateral dynamic readings as continuously measured by the ESP® sensor system. If vehicle stability is to be maintained, the longitudinal force when cornering must be controlled by means of engine torque regulation in such a way that there are sufficient reserves of lateral force at all times. In order to comply with this physical correlation, when cornering on road surfaces with a low friction coefficient the control thresholds for engine torque regulation at the wheels on the outside of the bend are reduced considerably so that the tyres can develop sufficient lateral force.

4MATIC: cutting-edge technology breaks new ground

The 4MATIC powertrain fitted in Mercedes-Benz passenger cars is one of


the best-performing permanent all-wheel drive systems on the market. The
basic design concept, with the engine installed longitudinally and the integral
transmission and transfer case unit, produces a compact, lightweight
arrangement that minimises frictional losses, heralding a number of benefits compared to other passenger car systems with a transverse power unit and
selectable 4x4. Depending on the particular model, fuel consumption, for
instance, is a mere 0.2 to 0.6 litres more per hundred kilometres than on
an equivalent vehicle with conventional drive, while vibration and acoustic
comfort meet the high standards expected of Mercedes-Benz vehicles.

CLS 4MATIC: stylish sportiness and dynamism in the winter too

Mercedes-Benz achieves the standard of driving dynamics which the CLS is


renowned for courtesy of the highly sophisticated DIRECT CONTROL suspension with adaptive shock absorbers. The weight-optimised DIRECT CONTROL system, featuring a three-link front suspension and multi-link independent rear
suspension, automatically adapts to the changing driving situation by varying the damping forces, resulting in a substantial improvement in ride comfort. The air suspension system – optional for the CLS 350 CDI 4MATIC BlueEFFICIENCY
and standard on the CLS 500 4MATIC BlueEFFICIENCY – is combined with a continuously variable, electronically controlled damping system that processes
a series of sensor signals and controls each wheel individually. So, not only do Mercedes customers experience the best in comfort, they reap the benefits of excellent handling safety and sporty agility too.

A snug interior with a clear view: THERMOTRONIC climate comfort

Carefully balanced control of the interior climate is especially important in the winter. This is why Mercedes-Benz offers the THERMOTRONIC luxury automatic climate control system. Apart from regulating the climate separately for the driver, front passenger and passengers in the rear, it allows individual
pre-settings to be programmed too. This system furthermore includes a pollutant sensor which automatically switches to air recirculation mode if it detects any sudden increase in the carbon monoxide or nitrogen oxide levels in the outside air – when driving through a tunnel, for instance. Another highlight of the THERMOTRONIC system is the residual heat function: pressing the "Rest" button heats or ventilates the passenger compartment for around 30 minutes when the engine is switched off.

THERMOTRONIC heats up the passenger compartment extremely efficiently,


even after a cold start on winter mornings. This is thanks to a heating output of eleven kilowatts, equivalent to the capacity of the central heating system in a modern family home. On the diesel models, a heat exchanger with six integral PTC heating elements (PTC = Positive Temperature Coefficient) is also activated when the outside temperature falls below a certain level in order to boost the effect of the main heat exchanger with an electrical output of around 1200 watts. The assistance from the 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 that they dissipate considerably less heat to the coolant under partial load conditions than conventional engines.

    Mercedes offers 4MATIC in 48 passenger car models

The Mercedes-Benz all-wheel drive line-up currently encompasses 48 passenger car models across ten model series and offers an impressively wide choice: besides the E-Class and the C-Class, which both come in saloon and estate variants, the 4MATIC portfolio is enriched by models from the S-Class, CL luxury coupé, CLS four-door coupé and R-Class touring SUV ranges too. There is also the compact GLK as well as the GL-Class and M-Class off-roaders. Still going strong after 30 years in production, the G-Class truly comes into its own off the beaten track and continues to rank as one of the best cross-country vehicles in the world.

    All-wheel drive development expertise since 1903

There is a reason why Mercedes engineers are so skilled in the development
of groundbreaking all-wheel drive concepts. The history of all-wheel drive at
Mercedes-Benz dates all the way back to 1903. Since then, the accepted maxim has been that all-wheel drive is the best technology for making quicker and safer progress under the most adverse conditions. Over the course of the years it has been successfully employed in a variety of Mercedes-Benz models. Some models, such as the G-Class and the Unimog, have attained legendary status all over the world. But all-wheel drive has its benefits in everyday operation on asphalt roads too, as demonstrated by the 4MATIC saloons from Mercedes-Benz. The innovative drive concept received its saloon premiere in the W 124 E-Class model series back in 1987. The 4ETS system made its debut aboard the M-Class in 1997.
Mercedes-Benz has therefore amassed a wealth of experience with these
electronic control systems – more in fact than any other car manufacturer.

Contacts:

Wolfgang Zanker, tel.: +49 (0)711 17-75847, wolfgang.zanker@daimler.com


Frank Bracke, tel.: +49 (0)711 17-75852, frank.bracke@daimler.com

Further information from Mercedes-Benz is available online at:



www.media.daimler.com



The automatic drive for wintry road conditions

Sure, predictable handling, plus impressive driving dynamics

As with the 4MATIC system's set-up on a dry or wet road, the directional stability and, therefore, the active safety of the 4MATIC models are paramount at all times when wintry conditions prevail, too. The mechanical principle of the 4MATIC system featuring a 45:55 torque split between the front and rear axles and the multi-disc limited-slip centre differential with a basic locking torque of 50 Newton metres offer all the right ingredients.

This basic design enables high levels of traction, firstly because the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. Secondly, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving on the limit, as a yellow warning symbol will flash in the instrument cluster. This serves as a prompt to adapt the driving style to the road conditions.

The drive mechanism's permanently engaged design offers key advantages over other systems that first need to diagnose a lack of grip before activating the
all-wheel drive. The 4MATIC will have already made use of this valuable time
to start transmitting drive torque via the wheels to the road.

All-wheel drive is not a substitute for winter tyres

Like any other all-wheel drive system, the 4MATIC has to abide by the laws of driving physics. The fundamental rule is that a tyre is only able to transfer a


certain level of overall force to the road surface. If a particularly high degree of longitudinal force is required during acceleration or braking, for example, the available lateral force is reduced. When cornering, the reverse applies: now a large amount of lateral force is required to keep the vehicle on course, while the longitudinal force potential is restricted. The engineers' skill in designing the drive mechanism and fine-tuning the control systems lies in their ability to
exploit these correlations in such a way as to ensure the best possible handling characteristics under all conditions. The frictional coefficient µ describes the physical grip between the tyres and the ground. This figure is high on a dry road (µ = 0.9) and low on a snow-covered road (µ = 0.3).

Despite all the engineers' efforts, it is ultimately the drivers themselves who


determine how safe they are out on the road. They should always adapt their
driving style in accordance with the wintry conditions and ensure that their
vehicle is suitably equipped; winter tyres are absolutely essential here.

Pulling away with ease on ice and snow

When starting off in wintry conditions, certain road surface conditions are


automatically detected and the interventions of the 4ETS electronic traction
control system adjusted so as to achieve the greatest possible acceleration while minimising wheel slip, ensuring optimum directional stability in the process. This strategy also allows the vehicle to pull away under the most adverse
conditions, such as when one side of the vehicle is on an icy slope (µ-split) or
both wheels on either the front or rear axle have limited grip (µ-jump).

When starting off on µ-split, one side of the vehicle is on snow or ice and the other on asphalt. This means there are major differences in the coefficient of


friction between the left and right-hand side of the vehicle. On all vehicles with open axle differentials, the wheel with the smallest friction coefficient limits the maximum transferable drive power. If the drive power exceeds the maximum transferable power, the wheels on snow or ice will start to spin and the vehicle would be unable to start off.

4ETS instantly detects this situation and prevents the wheels from spinning by building up exactly the right amount of pressure in the wheel brakes. As the wheel with the higher friction coefficient is now braced by the brake force at the wheel with the smaller friction coefficient, the 4MATIC model starts to move. After pulling away, the wheel characteristics are closely observed and the brake pressure regulated in such a way that, as far as possible, there is no difference


in speed between the individual wheels. The braking force applied by 4ETS
effectively simulates a higher coefficient of friction on the side of the road
covered with ice or snow; ideally, this will match the coefficient of friction on
the asphalt side. This produces an optimal inter-wheel locking effect at the axle differentials, resulting in the maximum possible acceleration on µ-split surfaces.

Starting off on "µ-jump" surfaces – where one of the vehicle's axles is entirely on ice or snow and the other on asphalt – is hampered by the large differences in friction coefficient between the front and rear wheels. On vehicles with an open inter-axle differential, the axle with the lower coefficient of friction determines the transferable drive power. Whilst the multi-disc differential lock with its basic locking torque of 50 Newton metres does have a balancing effect, it is unable to compensate for these extreme differences in friction coefficient. Here again, both wheels on the axle with the lower coefficient of friction start to spin if the drive power exceeds the maximum transferable drive power at this friction coefficient. The 4ETS resolves this problem by instantly detecting spinning wheels and


braking them. In this way, the braked axle with the smaller friction coefficient braces the axle with the higher friction coefficient – and the 4MATIC model starts to move.

Assured handling on wintry roads

On twisting roads covered with snow and ice, vehicle stability is primarily


controlled by the 4ETS system's acceleration skid control function regulating engine torque. The 4ETS control thresholds are adjusted according to the driving situation based on the vehicle's longitudinal and lateral dynamic readings as
continuously measured by the ESP® sensor system. To prevent the vehicle from tail-skidding, the longitudinal force when cornering must be controlled by means of engine torque regulation in such a way that there are sufficient reserves of lateral force at all times. In order to comply with this physical correlation, when cornering on road surfaces with a low friction coefficient vehicle stability is mainly controlled by the ESP® and ASR acceleration skid control systems
intervening to ensure that there is always sufficient lateral force in reserve.
Initially, only enough engine torque to allow the tyres to develop sufficient lateral force is transmitted to the wheels on the outside of the bend. If the ASR control function cannot restore directional stability, the ESP® system will intervene by applying the brakes to stabilise the vehicle.

In contrast to the control mechanisms triggered when cornering, considerably more longitudinal force can be provided when accelerating in a straight line, as the tyres hardly have to transfer any lateral force. What is important here is that the tyres can work in the optimum µ-slip curve range. In order to achieve this,


the control thresholds for engine torque regulation are raised in this driving situation. When driving on snow-covered or icy roads with low friction
coefficients, the multi-disc differential lock in the transfer case takes effect,
producing an inter-axle locking torque of 50 Newton metres in the powertrain. This locking effect boosts traction considerably without having any negative
impact on the control systems. When the final-drive ratios are factored in, this allows 150 Newton metres to be delivered to the wheels.

In certain wintry conditions it may become necessary to deactivate the control systems using the "ESP® OFF" switch. This is the case where high slip values are required at the wheels – when powering out of deep snow, for instance, either with or without snow chains. Even in "ESP OFF" mode, drivers can still count on the full support of the control systems when braking. Once back on a road surface with a normal covering of snow, the control systems should be reactivated again.



The current 4MATIC generation

Lighter, more compact, more efficient

Compared to the previous all-wheel drive technology, the latest generation of
the 4MATIC all-wheel drive system stands out for its higher efficiency, lower weight and more compact design. These advantages over the predecessor
models translate into superior traction and greater fuel economy. Depending on the particular model, this means that fuel consumption is a mere 0.2 to 0.6 litres or so more per hundred kilometres than on an equivalent vehicle with
conventional drive.

The latest-generation 4MATIC only adds 50 to 70 kilograms of extra weight


(depending on model) and boasts a compact design that now takes up less space. As a result, no modifications to the bodyshell are required and it does not
encroach on the front-passenger footwell. What's more, the compact design
helps to improve noise and vibration levels.

Transfer case integrated in 7G-TRONIC automatic transmission

The 4MATIC transfer case, featuring a planetary centre differential and a pair


of bevel gears acting as a lateral output to the front axle, is integrated into the
7G-TRONIC PUS automatic transmission that always comes as standard on the 4MATIC models. The centre differential produces the 45:55 torque split between the front and rear axles that has the aforementioned positive impact on handling stability and traction. Further highlights of the powertrain include the lateral output to the front axle as well as the rear universal joint that is integrated into the power take-off's output gear. This space-optimised design enables the front axle propshaft to be run very close to the transmission without having to modify the bodyshell in any way.

The higher efficiency of the 4MATIC drive system compared to the predecessor models is largely down to the omission of the gear stage for the transfer case's power take-off as well as an improved oil supply, since the integral design means that transmission and transfer case share the same oil circuit. This sophisticated 4MATIC technology together with the weight saving result in a substantial


reduction in fuel consumption.

    ADAPTIVE BRAKE: state-of-the-art brake control system ensures shortest stopping distances – even in wintry road conditions

The ADAPTIVE BRAKE control system incorporates the basic anti-lock braking system (ABS), acceleration skid control (ASR) and yaw control functions. ABS and ASR record and control the driving dynamics along the vehicle's longitudinal axis, while the yaw control looks after the lateral dynamics. If ADAPTIVE BRAKE diagnoses critical driving situations, corrective braking and control of drive torque are used to maintain or restore traction and directional stability as far
as is physically possible.

New additional braking functions make the ADAPTIVE BRAKE system even safer and more convenient. Hill-Start Assist prevents the vehicle from rolling in the opposite direction to that intended by the driver. The set of functions also


includes brake priming: should the driver suddenly release the accelerator, the system prepares for possible panic braking by pressing the brake pads lightly against the brake discs. If the brakes are indeed applied with full force, the
instantaneous build-up of pressure when the brake pedal is pressed shortens the stopping distance by a significant amount. Thanks to ADAPTIVE BRAKE's ability to produce even the smallest brake pressures with great precision, it is possible to remove the film of water which forms on the brake discs in wet conditions by gently applying the brakes for a brief time. This shortens the brakes' response time when driving in the wet, thus reducing the stopping distance even further. This function is triggered automatically once a certain number of windscreen wiper cycles has been reached and the driver has not applied the brakes in the meantime.

Four bestsellers involved in winter test

Exceptional traction combined with varying


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