Operating principle
The TCS switches on automatically when the engine is started and then conducts
a self-test. The system monitors the speeds of the driven wheels with the aid of
the ABS sensors. If the wheels are spinning, the force transmitted to the road sur-
face is automatically adapted by reducing the engine speed. The system operates
at all speeds.
The TCS operates in combination with the ABS ⇒ page 157,
Antilock brake system
(ABS). The TCS will not function if a fault exists in the ABS system.
The TCS warning light lights up in the instrument cluster when there is a fault on
the TCS ⇒ page 27.
During an intervention of the system, the TCS warning light flashes in the in-
strument cluster ⇒ page 27.
Switching off
You can also switch off the TCS system by pressing the ⇒ fig. 138 button, or, in ve-
hicles with ESP, by pressing the ⇒ fig. 137 button. The TCS warning light lights up
in the instrument cluster when the TCS is switched off .
The TCS should normally always be switched on. It may be good practice in certain
exceptional cases, such as when you wish to have wheel slip, to switch off the
system.
Examples:
● when driving with snow chains,
● when driving in deep snow or on a loose surface,
● when it is necessary to rock a car free when it has become stuck.
then you should switch on the TCS again.
TCS Off-road
After switching on the Off-road mode ⇒ page 160
, TCS Off-road is activated.
TCS Off-road provides a more effective acceleration of the vehicle on an unfirm
ground, as it allows higher traction between the slipping wheels and the ground.
The system operates when starting off or at low speeds. WARNING
You should always adjust your style of driving to the conditions of the road
surface and the traffic situation. The increased safety offered must not tempt
you to take greater risks than otherwise - risk of an accident! Note
● All four wheels must be fitted with the same tyres in order to achieve prob-
lem-free operation of the TCS. Differing rolling circumferences of the tyres can
lead to an undesirable reduction in the engine output.
● Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the TCS ⇒
page 207, Ac-
cessories, changes and replacement of parts.
Active driver-steering recommendation (DSR) This function indicates to the driver in critical situations a steering recommenda-
tion in order to stabilise the vehicle. The active driver-steering recommendation is
activated, for example, on the right and left vehicle side when braking sharply on
different road surfaces. WARNING
Even with this function the vehicle cannot steer itself! The driver is further-
more responsible for the steering of the vehicle!
Brakes What has a negative effect on braking efficiency?
Wear-and-tear
Wear-and-tear to the brake pads is greatly dependent on the operating conditions
of the vehicle and your style of driving. Particularly if you drive a great deal in
towns and over short distances or if you adopt a sporty style of driving, it may be
necessary to have the thickness of the brake pads inspected at a specialist garage
between the service inspections.
Wet roads or road salt
There may be a certain delay before the brakes take full effect under certain con-
ditions such as when driving through water, during heavy rain showers or after
the vehicle has been washed in an automatic vehicle wash, since the brake discs
and brake pads may be moist or even have a coating of ice on them in winter. You
should dry the brakes as soon as possible by applying and releasing the brakes
several times. £ 155
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There also may be a certain delay before the full braking efficiency is available
when driving on roads which have been treated with road salt if you have not
used the brakes for some considerable time beforehand. The layer of salt on the
brake discs and brake pads must first be rubbed off when you apply the brakes.
Corrosion
Corrosion on the brake discs and dirt on the bake pads occur if the vehicle has
been parked for a long period and if you do not make much use of the braking sys-
tem.
We recommend cleaning the brake discs by firmly applying the brakes at a fairly
high speed if you do not make much use of the braking system or if surface corro-
sion is present ⇒ .
Faults in the brake surface
If you notice that the braking distance has suddenly become longer and that the
brake pedal can be depressed further, it is possible that a brake circuit of the dual-
circuit brake system has failed. Drive, in such cases, to the nearest specialist ga-
rage without delay in order to have the problem rectified. Drive at a reduced
speed while on your way to the dealer and adapt your style of driving to the high-
er brake pedal pressure required.
Low brake fluid level
An insufficient level of brake fluid may result in problems in the brake system. The
level of the brake fluid is monitored electronically ⇒ page 29, Brake system . WARNING
● Only apply the brakes for the purpose of drying and cleaning the brake
discs if the traffic conditions permit this. Do not place any other road users in
jeopardy.
● When retrospectively mounting a front spoiler, solid wheel hubs etc. one
must ensure that the air supply to the front wheel brakes is not reduced oth-
erwise the braking system could run too hot.
● Allow for the fact that new brake pads do not achieve their full braking ef-
ficiency until approximately 200 kilometres. New brake pads must be first
“run in
” before they develop their optimal friction force. You can, however,
compensate for this slightly reduced braking force by increasing the pressure
on the brake pedal. This guideline also applies to any new brake pads installed
at a future date. CAUTION
● Never allow the brakes to rub by applying slight pressure if you do not wish to
brake the vehicle. This causes the brakes to overheat and can also result in a lon-
ger braking distance and excessive wear.
● Before negotiating a steep downhill section, please reduce your speed, shift
down into the next lower gear (manual gearbox) or select a lower driving stage
(automatic gearbox). This enables you to make full use of the braking power of
the vehicle and reduces the strain on the brakes. Any additional braking should be
done intermittently, not continuously. Note
The brake light flashes automatically in case of an emergency braking at speeds
greater than 60 km/h or with the intervention of the ABS, which lasts longer than
1.5 seconds. After the speed was reduced below 10 km/h or the vehicle was stop-
ped, the brake light stops flashing and the hazard warning light system switches
on. The hazard warning light system is switched off automatically after accelerat-
ing or driving off again.
Brake booster The brake booster boosts the pressure which you generate with the brake pedal.
The necessary pressure is only generated when the engine is running. WARNING
● Never switch off the engine before the vehicle is stationary.
● The brake booster only operates when the engine is running. Greater
physical effort for braking is required when engine is switched off. Because if
you do not stop as normal, this can cause an accident and severe injuries.
● While stopping or braking with a vehicle with a petrol engine and manual
transmission in the low rev range, press down on the clutch pedal. If you fail
to do so, the result may be an impairment of the function of the power brake.
You will apply a greater force to the brake pedal which you are usde to - dan-
ger of accident! 156
Intelligent technology
Antilock brake system (ABS)
ABS prevents the wheels locking when braking.
General
The ABS contributes significantly to enhancing the active safety of your vehicle.
Compared to a car not fitted with the ABS brake system, you are able to retain op-
timal steering ability even during a full brake application on a slippery road surface
because the wheels do not lock up.
You must not expect, however, that the braking distance will be shorter under all
circumstances as a result of the ABS. The braking distance for example on gravel
and fresh snow, when you should anyway be driving slowly and cautiously, will be
longer.
Operating principle
The brake pressure will be reduced on a wheel which is rotating at a speed which
is too low for the speed of the vehicle and tending to lock. This control cycle is
noticeable from a pulsating movement of the brake pedal which is accompanied
by noises. This is consciously intended to provide the driver with the information
that the wheels are tending to lock (ABS control range). You must always keep the
brake pedal depressed to enable the ABS to optimally control the brake applica-
tion in this braking range. Never interrupt the application of the brakes!
As soon as the vehicle speed has increased to about 20 km/hour an automatic
test procedure is conducted during which you will be able to hear a pumping noise
for about 1 second.
ABS Off-road
After switching on the Off-road mode ⇒ page 160, ABS Off-road is activated.
ABS Off-road increases the braking power of the vehicle on an unfirm ground, as it
keeps the wheels blocked for a longer period of time when the brake is applied
while sliding. The system is only available, if the front wheels are in the straight-
ahead position.
The system operates at speeds of up to 50
km/h. WARNING
● The ABS can also not overcome the physical limits of your vehicle. Please
do not forget this, particularly when driving on icy or wet road surfaces. If the
ABS is operating within the control range, adapt your speed immediately to
the conditions of the road surface and the traffic situation. The increased
safety offered by the ABS must not tempt you to take greater risks than oth-
erwise - risk of an accident!
● The normal braking system is still fully functional if there is an ABS fault.
Visit a specialist garage immediately and adjust your style of driving according
to the damage to the ABS as you will not know how great the damage is and
the limitation it is placing on the braking efficiency. Note
● A warning light comes on if a fault occurs in the ABS system ⇒
page 28.
● Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the ABS ⇒
page 207,
Accessories, changes and replacement of parts.
Brake Assist During a severe brake application (e.g. if a hazard exists), the Brake Assist increa-
ses the braking force and thus makes it possible to rapidly produce the pressure
required in the brake system.
The majority of drivers do apply the brakes in good time in dangerous situations,
but do not depress the brake pedal with sufficient pressure. Consequently, it is
not possible for the car to achieve its maximum deceleration and the car covers a
greater distance than necessary.
The Brake Assist is activated by the very quick operation of the brake pedal. In
such cases, a much greater braking pressure exists than during a normal brake ap-
plication. This makes it possible, even with a relatively low resistance of the brake
pedal, to produce an adequate pressure in the brake system in the shortest possi-
ble time, which is required for maximum deceleration of the car. You must apply
the brake pedal firmly and hold it in this position in order to achieve the shortest
possible braking distance. £ 157
Intelligent technology Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data
Basic setting of the system
After changing the tyre inflation pressures, after changing one or several wheels,
the position of a wheel on the vehicle (e.g. exchanging the wheels between the
axles) or when the warning light lights up while driving, a basic setting of the sys-
tem must be carried out as follows.
● Inflate all tyres to the specified inflation pressure ⇒ page 201.
● Switch on the ignition.
● Press button
⇒ fig. 139
for more than 2
seconds. While pressing the but-
ton, the warning light lights up. At the same time the memory of the system is
erased and the new calibration is started, which is confirmed with an audible sig-
nal and then the warning light goes out.
● If the warning light does not go out after the basic setting, there is a fault in
the system. Have the vehicle inspected by your nearest specialist garage.
Warning light lights up
If the tyre inflation pressure of at least one wheel is insufficiently inflated in com-
parison to the stored basic value, the warning light ⇒ lights up.
Warning light flashes
If the warning light flashes, there is a system fault. Have the vehicle inspected by
your nearest specialist garage. WARNING
● When the warning light lights up, immediately reduce the speed and
avoid sudden steering and brake manoeuvres. Please stop the vehicle without
delay at the nearest possible stop and inspect the tyres and their inflation
pressures.
● The driver is responsible for the correct tyre inflation pressures. For this
reason, the tyre inflation pressures must be checked regularly.
● Under certain circumstances (e.g. sporty style of driving, wintry or unpaved
roads) the warning light can be delayed or does not light up at all.
● The tyre pressure monitoring system does not take away the responsibility
from the driver for the correct tyre inflation pressure. Note
The tyre pressure monitoring system:
● does not replace the regular tyre inflation pressure control, because the sys-
tem cannot detect an even pressure loss; ●
cannot warn in case of very rapid tyre inflation pressure loss, e.g. in case of
sudden tyre damage. In this case carefully bring the vehicle to a standstill without
sudden steering movements and without sharp braking.
● In order to ensure a proper functioning of the tyre inflation pressure-control
system, it is necessary to carry out the basic setting again every 10 000 km or 1x a
year.
Diesel particle filter (diesel engine) In the diesel particle filter the resulting soot particles are collected
and burnt during the combustion of diesel fuel. Fig. 140 Vehicle data sticker
Code 7GG , 7MB or 7MG on the vehicle data sticker, see ⇒ fig. 140 , indicates that
your vehicle is equipped with a diesel particle filter. The vehicle data sticker is lo-
cated on the floor of the luggage compartment and is also stated in the Service
schedule.
The diesel particle filter filters the soot particles completely from the exhaust. The
soot is collected in the diesel particle filter and burnt regularly. To assist this pro-
cedure, we recommend not to drive regularly over short distances.
If the diesel particle filter is full or there is a fault, it is indicated by the warning
light . £ 159
Intelligent technology Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data
WARNING
● The diesel particle filter achieves very high temperatures. Therefore do not
park at points where the hot filter comes into direct contact with dry grass or
other combustible materials - risk of fire!
● Never use additional underbody protection or corrosion-protection agents
for the exhaust pipes, catalytic converters, diesel particle filter or heat shields.
When the engine reaches its operating temperature, these materials might ig-
nite – risk of fire. Note
When using diesel fuel with high sulphur content the life of the diesel particle fil-
ter is clearly reduced. A specialist garage will be able to tell you which countries
use only diesel fuel with high sulphur content.
Off-road General Fig. 141 Off-road switch
The Off-road mode comprises functions which assist off-road driving.
The following functions are integrated in the Off-road mode:
● Start-Off Assist ⇒ page 160,
● Downhill Drive Support ⇒ page 161 ,
● EDL Off-road ⇒ page 154,
● TCS Off-road ⇒ page 154,
● ABS Off-road ⇒ page 156. Switch on Off-road
The Off-road mode is switched on by pressing the button
⇒
fig. 141. The warning
light in the button lights up. The warning light lights up in the instrument cluster
if the system is switched on ⇒ page 30.
Switch off Off-road
The Off-road mode is switched off by repeated pressing of the button. The warn-
ing light in the button goes out. When switching off the ignition, the Off-road
mode is also switched off and can be switched on again, if necessary, after
switching on the ignition. If the engine is switched off by accident and restarted
within 30 seconds, the Off-road mode remains switched on.
All four wheels must be fitted with the same tyres in order to achieve proper op-
eration of the Off-road mode. Differing rolling circumferences of the tyres can lead
to an undesirable reduction in the engine output. WARNING
● Always adjust your speed to suit weather, road and traffic conditions. The
increased safety must not tempt you to take a greater safety risk than other-
wise - risk of accident!
● The Off-road equipment can also not overcome the physical limits of your
vehicle.
● The effect of the Off-road equipment depends as well on the tyres.
● The Off-road equipment is not designed for the use on common roads.
Start-Off Assist The Start-Off Assist enhances the driving comfort and can be used when starting
off, in particular on a slope. When the vehicle is stationary, the Start-Off Assist is
activated after switching it on using the button for the Off-road mode ⇒
fig. 141
.
Operating principle
When depressing the accelerator pedal fully, the engine speed required for the
start-up procedure of the stationary vehicle is restricted. The overspeed trip unit
is automatically deactivated after terminating the start-up procedure. As part of
the Assist System, the accelerator pedal is adapted in its characteristics for an
easier start-off on slippery and loose soil. 160
Intelligent technology
Downhill Drive Support
Operating principle
The Downhill Drive Support maintains a constant speed on a steep downhill sec-
tion when driving forwards and backwards by automatically intervening in the
brake system of all wheels. It prevents the wheels locking because the ABS re-
mains active. The warning light in the instrument cluster indicates that the
Downhill Drive Support is available ⇒ page 30.
The vehicle speed, which is maintained by the Assist System, is selected by the
driver while driving on a downhill section as of the moment the first intervention
of the Assist System is performed or else, while driving on a downhill section, the
driver must control the vehicle speed until the Assist System intervenes for the
first time. When the Assist System actively intervenes, this is indicated by the
warning light flashing or by a pulsating movement of the brake pedal, similar to
the intervention of the ABS.
You can increase or reduce the speed, even when no gear is engaged, by operat-
ing the accelerator or brake pedal. Thus the function is always interrupted and is
reactivated afterwards.
The Downhill Drive Support is activated automatically if the following conditions
are met:
● the Off-road mode is switched on and the warning light lights up in the in-
strument cluster,
● the engine of the vehicle is running and either the 1st, 2nd, 3rd gear, the re-
verse gear or no gear is engaged,
● the engine of the vehicle is running, the selector lever of the automatic gear-
box is in the position R, N, D, S or Tiptronic,
● the speed is less than 30 km/h,
● the downhill gradient is at least 10 % (when driving over sleepers the limit can
briefly drop to 8 %),
● neither the accelerator nor the brake pedal is operated.
It is however a requirement that the vehicle has sufficient grip on the soil. The
Downhill Drive Support cannot properly fulfil its function on slushy soil due to
physical reasons (ice or mud).
The Downhill Drive Support is deactivated when braking or accelerating or if the
downhill gradient is less than 8 %. Manual gearbox
The vehicle speed is steadily regulated by the Assist System depending on the
type of gearbox or engine:
● 1. gear - approx. 8 1)
- 30 km/h
● 2. gear - approx. 13 1 )
- 30 km/h
● 3. gear - approx. 22 1 )
- 30 km/h
● Reverse gear - approx. 9 1 )
- 30 km/h
● Neutral for driving forwards - as well as driving backwards - approx. 2 1 )
- 30
km/h
Automatic gearbox
● Selector lever in the position D, S or Tiptronic (for the 1st, 2nd, 3rd gear) for
driving forwards - approx. 2 - 30
km/h
● Selector lever in the position R for driving backwards - approx. 2 - 30 km/h
● Selector lever in the position N for driving forwards as well as backwards - ap-
prox. 2 - 30
km/h Note
● During an intervention of the Downhill Drive Support, the brake lights do not
light up.
● Do not switch off the Off-road mode during an intervention of the Assist Sys-
tem. 1)
The indicated values represent the average of the lower speed limits if a gear is engaged (depending
on the type of gearbox or engine). 161
Intelligent technology Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data
Driving and the environment
The first 1 500 kilometres and then afterwards
New engine The engine has to be run in during the first 1 500 kilometres.
Up to 1 000 kilometres
– Do not drive faster than 3/4 of the maximum speed of the gear in use, that is
3/4 of the maximum permissible engine speed.
– Do not use full throttle.
– Avoid high engine revolutions.
– Do not tow a trailer.
From 1 000 up to 1 500 kilometres
– Increase the power output of the engine gradually up to the full speed of the
gear engaged, that is up to the maximum permissible engine revolutions.
During the first operating hours the engine has higher internal friction than later
until all of the moving parts have harmonized. The driving style which you adopt
during the first approx.1 500 kilometres plays a decisive part in the success of run-
ning in your car.
You should not drive at unnecessarily high engine revolutions even after the run-
ning-in period is complete. The maximum permissible engine speed is marked by
the beginning of the red zone on the scale of the revolutions counter. Shift up in-
to the next higher gear on a vehicle fitted with manual gearbox before the red
zone is reached. During acceleration (depressing the accelerator) exceptionally
high engine speeds are automatically reduced, yet the engine is not protected
against too high engine speeds which are caused by incorrectly shifting down the
gears resulting in a sudden increase of the engine speeds above the permitted
maximum revolutions which can lead to engine damage.
For a vehicle fitted with a manual gearbox the converse situation also applies: Do
not drive at engine revolutions which are too low. Shift down as soon as the en-
gine is no longer running smoothly. CAUTION
All the speed and engine revolution figures apply only when the engine is at its
normal operating temperature. Never rev up an engine which is cold, neither when
the vehicle is stationary nor when driving in individual gears. For the sake of the environment
Not driving at unnecessarily high engine revolutions and shifting to a higher gear
as early as possible are ways to minimise fuel consumption and operating noise
levels and protects the environment.
New tyres New tyres have to be “run in” since they do not offer optimal grip at first. You
should take account of this fact for the first 500 kilometres and drive particularly
carefully.
New brake pads Allow for the fact that new brake pads do not achieve their full braking efficiency
until approximately 200 kilometres. New brake pads must be first “run in” before
they develop their optimal friction force. You can, however, compensate for this
slightly reduced braking force by increasing the pressure on the brake pedal.
This guideline also applies to any new brake pads installed at a future date.
During the running-in period, you should avoid excessive stresses on the brakes.
This includes, for example, violent braking, particularly from very high speeds, and
also when crossing mountain passes.
Catalytic converter Proper operation of the emission control system (catalytic convert-
er) is of major significance for driving your vehicle in an environ-
mentally conscious way.
Please refer to the following guidelines: £162
Driving and the environment
–
For vehicles with petrol engine only refuel with unleaded petrol ⇒ page 186,
Fuel.
– Never run the fuel tank completely empty.
– Do not switch off the ignition while you are driving the vehicle.
– Do not pour too much oil into the engine ⇒
page 192, Replenishing engine oil.
If you drive your vehicle in a country in which unleaded petrol is not available, you
must have the catalytic converter replaced later when driving the vehicle into a
country in which use of a catalytic converter is mandatory. WARNING
● In view of the high temperatures which may be produced in the catalytic
converter, one should always park a vehicle in such a way that the catalytic
converter cannot come into contact with easily flammable materials below the
vehicle - a risk of fire!
● Never use additional underbody protection or corrosion-protection agents
for the exhaust pipes, catalytic converters or heat shields. Such substances
might ignite when driving - risk of fire! CAUTION
● On vehicles fitted with a catalytic converter, never let the fuel tank run com-
pletely empty. An irregular fuel supply can result in poor ignition or misfiring. Un-
burnt fuel may get into the exhaust system and damage the catalytic converter.
● Filling the tank even only once with leaded petrol will result in the catalytic
converter being destroyed.
● If you detect misfiring, a drop in performance or irregular engine running when
driving, reduce your speed immediately and have the vehicle inspected by the
nearest specialist garage. The symptoms described may be caused by a fault in
the ignition system. Unburnt fuel may get into the exhaust system and damage
the catalytic converter. For the sake of the environment
Even if the exhaust system is operating properly, a sulphur-like exhaust odour
may be produced under certain operating conditions of the engine. This depends
on the sulphur content of the fuel. It is often sufficient to refuel with unleaded
premium-grade petrol of a different brand or at a different filling station. Driving in an economical and environmentally
conscious manner
General Your personal style of driving is a major factor.
Your fuel consumption, any pollution of the environmental and the wear-and-tear
to the engine, brakes and tyres, depend essentially on three factors:
● your personal style of driving,
● the conditions under which your vehicle is operated,
● technical aspects.
You can easily improve your fuel economy by 10 - 15 percent by driving in an eco-
nomical way with foresight. This section is intended to provide you with a number
of tips on how to protect the environment and at the same time save money.
The fuel consumption can naturally also be influenced by factors which are be-
yond the driver's control. It is, for example, normal for the fuel consumption to in-
crease in winter and under worsened conditions such as poor road conditions,
towing a trailer, etc.
The technical requirements for low fuel usage and economic efficiency of the ve-
hicle have already been built into the vehicle at the works. Special attention has
been given to minimising negative effects on the environment. It is necessary to
take note of the guidelines given in this chapter in order to make best use of
these characteristics and to maintain their effectiveness.
The optimal engine speed should be obtained when accelerating, in order to avoid
a high fuel consumption and resonance of the vehicle.
Looking ahead when driving A vehicle's highest fuel consumption occurs it accelerates.
Avoid accelerating and braking unnecessarily. If you drive with foresight you will
not need to brake so often and will also then not have to accelerate so much. Let
your vehicle coast to a stop, for example, if this is possible, when you see that the
next set of traffic lights is at red. 163
Driving and the environment Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data