Seat belts
Why seat belts? Fig. 116 Driver wearing seat belt
It is a proven fact that seat belts offer good protection in accidents ⇒ fig. 116 . Thus
wearing a seat belt is a legal requirement in most countries.
Seat belts which have been correctly fastened and adjusted hold the occupants of
the car in the correct seated position ⇒ fig. 116 . The seat belts reduce the kinetic
energy (energy of motion) to a considerable extent. They also prevent uncontrol-
led movements which, in turn, may well result in severe injuries.
The occupants of a vehicle who have fastened and correctly adjusted their seat
belt, profit to a major extent from the fact that the kinetic energy is optimally ab-
sorbed by the belts. The structure of the front end of the vehicle and other pas-
sive safety measures, such as the airbag system, also contribute to reducing the
kinetic energy. The energy produced is thus absorbed and there is less risk of in-
jury.
Accident statistics prove that seat belts which are fastened and properly adjusted
reduce the risk of an injury and enhance the chance of survival in a major accident
⇒ page 132.
It is important that you pay attention to safety measures, particularly when trans-
porting children in the vehicle ⇒
page 146, What you should know about trans-
porting children!. WARNING
● Fasten your seat belt each time before setting off - also when driving in
town! This also applies to the people seated at the rear - risk of injury!
● Expectant women must also always wear a seat belt. This is the only way
of ensuring optimal protection for the unborn child ⇒ page 134, How are seat
belts correctly fastened?
.
● It is important for the belt webbing to be properly routed if the seat belts
are to offer the maximum protection. You can see a description of how safety
belts should be fitted properly on the next pages. Note
Please comply with any differing legal requirements when using the seat belts.
The physical principle of a frontal collision Fig. 117 The driver is catapulted forward if not wearing a belt/The rear seat occupant is cata-
pulted forward if not wearing a belt
The physical principle of a frontal accident can be explained quite simply:
Motion energy, so-called kinetic energy, is produced as soon as the vehicle is mov-
ing, both for the vehicle and its occupants. The magnitude of this kinetic energy
depends essentially on the speed at which the vehicle is travelling and on the
weight of the vehicle including the occupants. The greater the speed and weight
increase, the greater the amount of energy which has to be absorbed in the event
of an accident. £132
Seat belts
Driving Tips
Intelligent technology Electronic stability programme (ESP)
General Fig. 137 ESP system: Switch for TCS
The ESP aids you in maintaining control of your vehicle in situations in which the
vehicle is driving at its dynamic limits, such as entering a curve fast. The risk of
skidding is reduced and your car thus offers greater driving stability depending on
the conditions of the road surface. The system operates at all speeds.
The following systems are integrated into the electronic stability programme:
● Electronic Differential Lock (EDL),
● Traction control system (TCS),
● active driver-steering recommendation (DSR),
● Antilock brake system (ABS),
● Brake Assist,
● Uphill Start Assist.
The ESP system cannot be switched off with the
⇒ fig. 137 button; only the TCS
system is switched off, the warning light in the instrument cluster lights up. Operating principle
The ESP switches on automatically when the engine is started and then conducts
a self-test. The ESP control unit processes data from the individual systems. It al-
so processes additional measurement data which are supplied by highly sensitive
sensors: the rotational velocity of the vehicle about its vertical axis, the lateral ac-
celeration of the vehicle, the braking pressure and the steering angle.
The direction which the driver wishes to take is determined based on the steering
angle and the speed of the vehicle and is constantly compared with the actual be-
haviour of the vehicle. If differences exist, such as the car beginning to skid, the
ESP will automatically brake the appropriate wheel.
The car is stabilised again by the forces which take effect when the wheel is
braked. Intervention into the brake system takes place primarily on the outer front
wheel of a vehicle which tends to oversteer (tendency for the rear of the vehicle
to break away) while occurs this is on the inner rear wheel of a vehicle which
tends to understeer (tendency to shift out of the curve). This braking control cycle
is accompanied by noises.
During an intervention of the system, the warning light flashes in the instru-
ment cluster ⇒
page 27.
The ESP operates in combination with the ABS ⇒ page 157, Antilock brake system
(ABS). If there is a fault in the ABS system, the ESP also does not operate.
The ESP warning light lights up in the instrument cluster when there is a fault on
the ESP ⇒ page 27. WARNING
It is also not possible for the ESP to overcome the physical limits of the vehi-
cle. Even if a vehicle fitted with ESP you should still always adapt your style of
driving to the condition of the road surface and the traffic situation. This par-
ticularly applies when driving on slippery and wet roads. The increased safety
offered must not tempt you to take greater risks than otherwise - risk of an
accident! £ 153
Intelligent technology Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data
Note
● All four wheels must be fitted with the same tyres in order to achieve prob-
lem-free operation of the ESP. 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 ESP ⇒
page 207,
Accessories, changes and replacement of parts.
Electronic Differential Lock (EDL) The electronic differential lock prevents an individual wheel from
slipping.
General
The EDL makes it much easier, and sometimes at all possible, to start off, acceler-
ate and climb a steep hill when the conditions of the road surface are unfavoura-
ble.
Operating principle
The EDL is activated automatically, that is without any action on the part of the
driver. It monitors the speeds of the driven wheels with the aid of the ABS sen-
sors. Should only
one drive wheel begin spinning on a slippery surface there will
be an appreciable difference in the speed of the driven wheels. The EDL function
brakes the slipping wheel and the differential transmits a greater driving force to
the other driven wheel. This control process is also accompanied by noises.
Overheating of the brakes
The EDL switches off automatically if unusually severe stresses exist in order to
avoid excessive heat generation in the disc brake on the wheel which is being
braked. The vehicle can continue to be driven and has the same characteristics as
a vehicle not fitted with EDL.
The EDL switches on again automatically as soon as the brake has cooled down.
EDL Off-road
After switching on the Off-road mode ⇒ page 160
, EDL Off-road is activated.
EDS Offroad assists vehicle traction when driving on unfirm ground.
EDL is activated earlier in the Off-road mode than in the normal mode. The brake
pressure builts up more quickly on the slipping wheel, on one axle, as well as diag-
onally. WARNING
● Carefully depress the accelerator when accelerating on uniformly slippery
road surfaces, such as ice and snow. The driven wheels might still spin despite
the EDL and affect the stability of the vehicle - risk of an accident!
● You should always adapt your style of driving to the condition of road sur-
face and to the traffic situation even when your vehicle is fitted with EDL. The
increased safety offered must not tempt you to take greater risks than other-
wise - risk of an accident! Note
● If the ABS or ESP warning light comes on, this may also indicate a fault in the
EDL. Have the vehicle inspected by your specialist garage as soon as you can.
● 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 EDL ⇒
page 207,
Accessories, changes and replacement of parts.
Traction control system (TCS) The traction control system prevents the driven wheels from spin-
ning when accelerating.
Fig. 138 TCS switch
General
The TCS makes it much easier, and sometimes at all possible, to start off, acceler-
ate and climb a steep hill when the conditions of the road surface are unfavoura-
ble. £154
Intelligent technology
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
Intelligent technology Using the system Safety Driving Tips General Maintenance Breakdown assistance Technical data
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
The Brake Assist is able to help you achieve a shorter braking distance in emer-
gency situations by rapidly producing the pressure required in the brake system. It
fully exploits the attributes of the ABS. After you release the brake pedal, the
function of the Brake Assist is automatically switched off and the brakes operate
in the normal way.
The Brake Assist is part of the ESP system. If a fault occurs in the ESP, the Brake
Assist function is also not available. Further information on the ESP
⇒ page 153.WARNING
● The Brake Assist is also not able to overcome the physical limits of your car
in terms of the braking distance required.
● Adapt your speed to the conditions of the road surface and to the traffic
situation.
● The increased safety offered by the Brake Assist must not tempt you to
take a greater safety risk than otherwise.
Uphill Start Assist The uphill start assist makes it easier to start off on steep hills. The system assists
a start off by holding the brake pressure produced by the brake pedal actuation
for approx. 2 seconds after releasing the brake pedal. The driver can therefore
move his foot from the brake pedal to the accelerator pedal and start off on the
slope, without having to actuate the handbrake. The brake pressure drops gradu-
ally the more you operate the accelerator pedal. If the vehicle does not start off
within 2 seconds, it starts to roll back.
The uphill start assist is active as of a 3 % slope, if the driver door is closed. It is
always active on slopes when in forward or reverse start off. When driving down-
hill, it is inactive.
Electromechanical power steering The power steering enables you to steer the vehicle with less physical force.
With the electromechanical power steering, the steering assist is automatically
adapted to the speed and to the steering angle.
It is still possible to fully steer the vehicle if the power steering fails or if the en-
gine is not running (vehicle being towed in). The only difference is that greater
physical effort is required. If there is a fault in the power steering, the warning light
or lights up in the
instrument cluster ⇒
page 25. WARNING
Contact your specialist garage if the power steering is defective.
Tyre pressure monitoring system Fig. 139 Button for setting the tyre in-
flation pressure control value
The tyre pressure monitoring system compares with the aid of the ABS sensors
the speed and also the rolling circumference of the individual wheels. If the rolling
circumference of a wheel is changed, the warning light
in the instrument clus-
ter ⇒ page 28 and an acoustic signal sounds.
The rolling circumference of the tyre can change if:
● the tyre inflation pressure is too low,
● the structure of the tyre is damaged,
● the vehicle is loaded on one side,
● the wheels of an axle are loaded heavily (e.g. when towing a trailer or when
driving uphill or downhill),
● snow chains are mounted,
● the temporary spare wheel is mounted,
● one wheel per axle was changed. £158
Intelligent technology
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