Intelligent Technology217
Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
possible (by applying and releasing the brakes several times, if the road
conditions and the traffic situation allows it).
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 system.
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 corrosion 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 garage 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 higher 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 40,
“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 otherwise the braking system could run too hot.
•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 fric-
tion 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 longer 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.
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 (continued)
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Intelligent Technology
218
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.
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 optimal 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 application in this braking
range. Never interrupt the application of the brakes!
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 immediatel y 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 otherwise -
risk of an accident!
•The normal braking system is still fully functional if there is an
ABS fault. Visit a specialist garage as quickly as possible and
adjust your style of driving to take account of the ABS fault in the
meantime since you will not know how great the damage is.
Note
•A warning light comes on if a fault occurs in the ABS system
⇒ page 38.
•Changes to vehicle (e.g. on engine, on the brakes, on chassis or other
assignment of tyres and wheels) can influence the function of the ABS
⇒ page 270, “Accessories, changes and replacement of parts”.
Brake Assist*
During a severe brake application (e.g. if a hazard exists), the Brake
Assist increases 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 situ-
ations, but do not depress the brake pedal with sufficient pressure. Conse-
quently, it is not possible for the car to achieve its maximum deceleration
and the car covers a greater distance than necessary.
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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 application. 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 possible 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.
The Brake Assist is able to help you achieve a shorter braking distance in
emergency 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 213.
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 off-Assist*
The uphill-start off-assist makes it much 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 gradually 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 off-assist is active in the event of a 5% slope, if the vehicle
door is closed. It is always active on slopes when in forward or reverse
start off. When driving downhill, 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 automat-
ically 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
engine 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, a red or yellow warning light
lights up in the instrument cluster ⇒page 33.
WARNING
Contact your specialist garage if the power steering is defective.
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Intelligent Technology
220
Tyre inflation pressure-control system*
The tyre inflation pressure-control 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
lights up in the dash panel insert ⇒page 38. The rolling circumfer-
ence 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. Basic setting of tyre inflation pressure-control system
After changing the tyre inflation pressures or after changing one or several
wheels, the button for the tyre inflation pressure-control system must be
pressed long enough until an acknowledegment tone sounds when the
ignition is switched on.
•Inflate all tyres to the specified inflation pressure
⇒page 264.
•Switch on the ignition.
•Press the button ⇒ fig. 182 long enough, until an acknowledg-
ment tone sounds, which confirms the storage of the basic values. As long
as the button
is pressed, the warning light lights up in the instru-
ment .
Warning light
lights up
If the tyre inflation pressure of at least one wheel is insufficiently inflated
in comparison 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 regu-
larly.
•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.
Fig. 182 Button for
setting the tyre infla-
tion pressure control
value
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Driving and the Environment
222
New brake pads
Allow for the fact that new brake pads do not achieve their full braking effi-
ciency 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 pres-
sure 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
converter) is of major significance for driving your vehicle
in an environmentally conscious way.
Please refer to the following guidelines:
– For vehicles with petrol engine only refuel with unleaded petrol
⇒page 242, “Grades of petrol”.
– 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 252, “Replen-
ishing engine oil”. – Do not tow-start the vehicle over a distance of more than 50
metres ⇒page 286, “Tow-starting a vehicle”.
If you drive your vehicle in a country in which unleaded petrol is not avail-
able, 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-protec-
tion agents for the exhaust pipes, catalytic converters or heat
shields. Such substances might ignite when driving - risk of fire!
Caution
•Vehicles fitted with catalytic converter should never be allowed to let
the fuel tank to run completely empty. An irregular fuel supply can result
in poor ignition or misfiring. Unburnt 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 cata-
lytic 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.
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Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
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 economical 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 beyond the driver's control. It is, for example, normal for the fuel
consumption to increase 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 vehicle have already been built into the vehicle at the works. Special
attention has been given to minimising negative effects on the environ-
ment. 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.
Looking ahead when driving
A vehicle's highest fuel consumption occurs when it accel-
erates.
Avoid accelerating and braking unnecessarily. If you drive with forsight
you will not need to brake so often and will also then not have to accel-
erate 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.
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Towing a trailer
230
Distribution of the load
Distribute the load in the trailer in such a way that any heavy items are
located as close as possible to the axle. Secure the items to prevent them
slipping.
Tyre inflation pressure
Select the tyre inflation pressure on your vehicle for that of “fully laden”,
⇒ page 264. The inflation pressure of the tyres fitted to the trailer adjust in
accordance with the manufacturer's recommendation.
Exterior mirrors
You have to have additional exterior mirrors fitted if you are not able to see
the traffic behind the trailer with the standard rear-view mirrors. Both exte-
rior mirrors should be attached to folding arms. Adjust the mirrors so that
they provide you with an adequate field of view to the rear.
Headlights
Before starting off with a hitched trailer, also check the setting of the head-
lights. Alter the setting as necessary with the aid of the headlight beam
adjuster ⇒page 67.
Detachable ball head
The ball rod is detachable on vehicles which feature a factory-fitted towing
device. It is stowed together with separate fitting instructions in the spare
wheel well in the luggage compartment of the vehicle.
Further information on the towing device ⇒page 231.
Note
•We recommend that you also have your vehicle inspected between
service intervals if you tow a trailer frequently.
•The handbrake on the towing vehicle must be put on when coupling
and decoupling the trailer.
Driving Tips
Particular caution is required when towing a trailer.
– Do not, as far as possible, drive with your vehicle unladen and the trailer laden.
– Do not make full use of the legal maximum speeds. This applies in particular to downhill sections.
– Apply the brakes in good time.
– Keep a check on the coolant temperature gauge if the outside temperature is high.
Distribution of weight
The distribution of the weight is very poor if your vehicle is unladen and
the trailer is laden. Maintain a particularly low speed if you cannot avoid
driving with this combination.
Driving speed
Do not drive faster than 80 km/hour for safety reasons. This also applies
for countries in which higher speeds are allowed.
The fact that the driving stability of the vehicle + trailer combination
reduces with increasing speed means that the legally allowed speed
should not be used when there are unfavourable road, weather or wind
conditions, particularly near accident black spots.
You must always reduce your speed immediately as soon as you detect
even just the slightest swaying of the trailer. On no account attempt to
stop the trailer from “swaying” by accelerating.
Apply the brakes in good time! If the trailer is fitted with a trailer brake ,
apply the brakes gently at first, then brake firmly. This will avoid brake jolts
resulting from the trailer wheels locking. Shift down gears in good time
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Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
before negotiating a downhill section to allow the engine to also act as a
brake.
Engine overheating
Please keep a check on the coolant temperature gauge if you have to
negotiate a lengthy slope in a low gear at a high engine speed when the
outside temperature is very high
⇒page 14.
If the needle of the coolant temperature gauge moves into the right-hand
area or even the red area of the scale, reduce your speed immediately.
Stop and switch off the engine if the warning light
in the instrument
cluster begins flashing. Wait a few minutes and check the level of coolant
in the coolant expansion bottle ⇒page 254, “Inspecting the coolant level”.
Please refer to the following guidelines ⇒page 35, “Coolant tempera-
ture/coolant level ”.
The coolant temperature can be reduced by switching on the heating.
Any increase in the cooling effect of the coolant fan through shifting down
a gear and increasing the engine speed is not possible since the fan
speed is independent of the engine speed. One should also not drop a
gear for this reason when towing a trailer as long as the engine can
manage the slope without any drop in speed.
Detachable ball head*
The detachable ball head of the towing device is stowed in a box for the
car tool kit in the spare wheel well in the luggage compartment.
An instruction for correct installation and removal of the ball head of the
towing device is supplied with the ball head
Inspect the ball head to ensure that it is properly locked each time before
setting off. The inspection is performed by turning the closed locking lever
downwards. If the locking lever can only be turned around a small angle
(approx. 5°), the locking mechanism is O.K. After the inspection pull the
locking lever back again to its stop. The towing device must not be used,
if it does not wish to close or the locking lever turns slightly in the closed
position.
Fig. 186 Detachable
ball head
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