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Driving183
Safety First
Operating Instructions
Practical Tips
Technical Specifications
When you increase speed with the accelerator and then release the pedal, the
system will automatically restore the set speed. This will not be the case,
however, if the vehicle speed is more than 10 km/h higher than the stored
speed for longer than 5 minutes. The speed will have to be stored again.
Cruise control is switched off if you reduce speed by depressing the brake
pedal. You can reactivate the control by pressing once on the upper part of the
rocker switch
RES/+ ⇒ page 182, fig. 133 .
WARNING
It is dangerous to use a set speed which is too high for the current road,
traffic or weather conditions. Risk of accident.Switching off the system temporarily*The cruise control system will be switched off in the following situations:•if the brake pedal is depressed,
•if the clutch pedal is depressed,•if the vehicle is accelerated to over 180 km/h,•when the lever is moved to the position “CANCEL” without reaching
the “OFF” position. Once the “CANCEL” operation is completed, the lever is
released and returns to its initial position.
To resume the cruise control, release the brake or clutch pedal or reduce the
vehicle speed to less than 180 km/h and press once on the upper part of the
rocker switch RES/+ ⇒ fig. 134 .WARNING
It is dangerous to use a set speed which is too high for the current road,
traffic or weather conditions. Risk of accident.Turning off the cruise control system*
AA
Fig. 134 Turn signal and
main beam headlight
lever: switch and rocker
switch for the cruise
control
AB
AA
Fig. 135 Turn signal and
main beam headlight
lever: switch and rocker
switch for the cruise
control
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Driving
184Vehicles with a manual gearbox
The system is completely turned off by moving the control all the way to
the right hand side (OFF engaged), or when the vehicle is stationary, ignition
off.
Vehicles with automatic gearbox / DSG automatic gearbox
To completely disengage the system, the selector lever must be placed in one
of the following positions: P, N , R or 1 or with the vehicle stopped and the
ignition turned off.
AB
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Intelligent technology185
Safety First
Operating Instructions
Practical Tips
Technical Specifications
Practical TipsIntelligent technologyBrakesBrake servoThe brake servo increases the pressure you apply to the brake pedal. It works
only when the engine is running .
If the brake servo is not functioning due to a malfunction, or if the vehicle has
to be towed, you will have to press the brake pedal considerably harder to
make up for the lack of servo assistance.
WARNING
The braking distance can also be affected by external factors.•Never let the vehicle coast with the engine switched off. Failure to do so
could result in an accident. The braking distance is increased considerably
when the brake servo is not active.•If the brake servo is not working, for example when the vehicle is being
towed, you will have to press the brake pedal considerably harder than
normal.
Hydraulic Brake Assist (HBA)*
The Hydraulic Brake Assist function (HBA) is only included in
vehicles with ESP.In an emergency, most drivers brake in time, but not with maximum force.
This results in unnecessarily long braking distances.
This is when the brake assist system comes into action. When pressing the
brake pedal rapidly, the assistant interprets it as an emergency. It then very
quickly builds up the full brake pressure so that the ABS can be activated
more quickly and efficiently, thus reducing the braking distance.
Do not reduce the pressure on the brake pedal. The brake assist system
switches off automatically as soon as you release the brake.
Emergency braking warning
If the vehicle is braked suddenly and continuously at a speed of more than 80
km/h, the brake light flashes several times per second to warn vehicles
driving behind. If you continue braking, the hazard warning lights will come
on automatically when the vehicle comes to a standstill. They switch off auto-
matically when the vehicle starts to move again.
WARNING
•The risk of accident is higher if you drive too fast, if you do not keep
your distance to the vehicle in front, and when the road surface is slippery
or wet. The increased accident risk cannot be reduced by the brake assist
system.
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Intelligent technology
186•The brake assist system cannot defy the laws of physics. Slippery and
wet roads are dangerous even with the brake assist system! Therefore, it is
essential that you adjust your speed to suit the road and traffic conditions.
Do not let the extra safety features tempt you into taking any risks when
driving.
Anti-lock brake system and traction control
M-ABS (ABS and TCS)Anti-lock brake system (ABS)
The anti-lock brake system prevents the wheels locking
during braking.The anti-lock brake system (ABS) is an important part of the vehicle’s active
safety system.
How the ABS works
If one of the wheels is turns too slowly in relation to the road speed, and is
close to locking, the system will reduce the braking pressure for this wheel.
The driver is made aware of this control process by a pulsating of the brake
pedal and audible noise. This is a deliberate warning to the driver that one or
more of the wheels is tending to lock and the ABS control function has inter-
vened. In this situation it is important to keep the brake pedal fully depressed
so the ABS can regulate the brake application. Do not “pump”.
If you brake hard on a slippery road surface, the best possible control is
retained as the wheels do not lock. However, ABS will not necessarily gu
arantee shorter braking distances in all
conditions. The braking distance could even be longer if you brake on gravel
or on fresh snow covering a slippery surface.
WARNING
•The anti-lock brake system cannot defy the laws of physics. Slippery
and wet roads are dangerous even with ABS! If you notice that the ABS is
working (to counteract locked wheels under braking), you should reduce
speed immediately to suit the road and traffic conditions. Do not let the
extra safety features tempt you into taking any risks when driving.•The effectiveness of ABS is also determined by the tyres fitted
⇒ page 237.•If the running gear or brakes are modified, the effectiveness of the ABS
could be severely limited.
Traction control system (TCS)
The traction control system prevents the drive wheels from
spinning when the vehicle is accelerating.Description and operation of the traction control system during acceleration
(TCS)
TCS reduces engine power to help prevent the drive wheels of front-wheel
drive vehicles losing traction during acceleration. The system works in the
entire speed range in conjunction with ABS. If a malfunction occurs in the
ABS, the TCS will also be inoperative.
TCS helps the vehicle to start moving, accelerate and climb a gradient in slip-
pery conditions where this may otherwise be difficult or even impossible.
T h e T C S i s s wi tch e d o n a u t o m a t i ca ll y w h e n t h e e n g i n e i s s t a r te d . I f n e ce s sa r y,
it may be turned on or off pushing the button on the centre console.
WARNING (continued)
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Intelligent technology187
Safety First
Operating Instructions
Practical Tips
Technical Specifications
When the TCS is off, the warning lamp is lit. The TCS should normally
be left on. Only in exceptional circumstances, when the slipping of the wheels
is required, should it be disconnected, for example
•With compact temporary spare wheel.•When using the snow chains.•When driving in deep snow or on soft terrain.•When the vehicle is bogged-down, to free it by rocking.
The TCS should be switched on again as soon as possible.WARNING
•It must be remembered that TCS cannot defy the laws of physics. This
should be kept in mind, particularly on slippery and wet roads and when
towing a trailer.•Always adapt your driving style to suit the condition of the roads and
the traffic situation. Do not let the extra safety afforded by TCS tempt you
into taking any risks when driving, this can cause accidents.Caution
•In order to ensure that TCS function correctly, all four wheels must be
fitted with the same tyres. Any differences in the rolling radius of the tyres can
cause the system to reduce engine power when this is not desired.•Modifications to the vehicle (e.g. to the engine, the brake system, running
gear or any components affecting the wheels and tyres) could affect the effi-
ciency of the ABS and TCS.
XDS*
Driveshaft differentialWhen taking a bend, the driveshaft differential mechanism allows the outer
wheel to turn at a higher speed than the inner wheel. In this way, the wheel
that is turning faster (outer wheel) receives less drive torque than the inner
wheel. This may mean that in certain situations the torque delivered to the
inner wheel is too high, causing the wheels to spin. On the other hand, the
outer wheel is receiving a lower drive torque than it could transmit. This
causes an overall loss of lateral grip on the front axle, resulting in understeer
or “lengthening” of the trajectory.
By using the ESP sensors and signals, the XDS system is able to detect and
correct this effect.
Through the ESP, the XDS brakes the inner wheel, thereby counteracting the
excess drive torque in this wheel. This means that the driver’s desired trajec-
tory is much more precise,
The XDS system operates in combination with the ESP and is always active,
even when the traction control, TCS, is disconnected.Electronic Stability Programme (ESP)*General notes
The Electronic Stability Programme increases the vehicle’s
stability on the road.The Electronic Stability Programme helps reduce the danger of skidding.
The Electronic Stability Programme (ESP) consists of ABS, EDL, TCS and
Steering manoeuvre recommendations.
OFF
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Intelligent technology
188Electronic Stability Programme (ESP)*
ESP reduces the danger of skidding by braking the wheels individually.
The system uses the steering wheel angle and road speed to calculate the
changes of direction desired by the driver, and constantly compares them
with the actual behaviour of the vehicle. If the desired course is not being
maintained (for instance, if the vehicle is starting to skid), then the ESP
compensates automatically by braking the appropriate wheel.
The forces acting on the braked wheel bring the vehicle back to a stable
condition. If the vehicle tends to oversteer, the system will act on the front
wheel on the outside of the turn.
Steering manoeuvre recommendations
This is a complementary safety function included in the ESP This function aids
the driver to better stabilize the vehicle in a critical situation. For example, in
case of sudden braking surface with varied adherence, the vehicle will tend
to destabilise its trajectory to the right or to the left. In this case the ESP
recognizes the situation and helps the driver with a counter steering
manoeuvre from the power steering.
This function simply provides the driver with a recommended manoeuvre in
critical situations.
The vehicle does not steer itself with this function, the driver has full control
of the vehicle at all times.
WARNING
•It must be remembered that ESP cannot defy the laws of physics. This
should be kept in mind, particularly on slippery and wet roads and when
towing a trailer.•Always adapt your driving style to suit the condition of the roads and
the traffic situation. Do not let the extra safety afforded by ESP tempt you
into taking any risks when driving, as this can cause accidents.
Caution
•In order to ensure that ESP functions correctly, all four wheels must be
fitted with the same tyres. Any differences in the rolling radius of the tyres can
cause the system to reduce engine power when this is not desired.•Modifications to the vehicle (e.g. to the engine, the brake system, running
gear or any components affecting the wheels and tyres) could affect the effi-
ciency of the ABS, EDL, ESP and TCS.Anti-lock brake system (ABS)The anti-lock brake system prevents the wheels locking during braking
⇒ page 186.Electronic differential lock (EDL)*
The electronic differential lock helps prevent the loss of trac-
tion caused if one of the driven wheels starts spinning.EDL helps the vehicle to start moving, accelerate and climb a gradient in slip-
pery conditions where this may otherwise be difficult or even impossible.
The system will control the revolutions of the drive wheels using the ABS
sensors (in case of an EDL fault the warning lamp for ABS lights up)
⇒ page 84.
At speeds of up to approximately 80 km/h, it is able to balance out differ-
ences in the speed of the driven wheels of approximately 100 rpm caused by
a slippery road surface on one side of the vehicle. It does this by braking the
wheel which has lost traction and distributing more driving force to the other
driven wheel via the differential.
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Intelligent technology189
Safety First
Operating Instructions
Practical Tips
Technical Specifications
To prevent the disc brake of the braking wheel from overheating, the EDL cuts
out automatically if subjected to excessive loads. The vehicle will continue to
function normally without EDL. For this reason, the driver is not informed that
the EDL has been switched off.
The EDL will switch on again automatically when the brake has cooled down.
WARNING
•When accelerating on a slippery surface, for example on ice and snow,
press the accelerator carefully. Despite EDL, the driven wheels may start to
spin. This could impair the vehicle’s stability.•Always adapt your driving style to suit road conditions and the traffic
situation. Do not let the extra safety afforded by EDL tempt you into taking
any risks when driving, this can cause accidents.Caution
Modifications to the vehicle (e.g. to the engine, the brake system, running
gear or any components affecting the wheels and tyres) could affect the effi-
ciency of the EDL ⇒page 212.The traction control system (TCS)The traction control system prevents the drive wheels from spinning when the
vehicle is accelerating ⇒page 186.
All-wheel drive*
On all-wheel drive models, the engine power is distributed to
all four wheelsGeneral notes
The all-wheel drive system operates completely automatically. The propul-
sion force is distributed among the four wheels and adapted to the driving
style and the road conditions.
The all-wheel drive is specially designed to complement the superior engine
power. This combination gives the vehicle exceptional handling and perform-
ance capabilities, both on normal roads and in more difficult conditions, such
as snow and ice.
Winter tyres
Thanks to its all-wheel drive, your vehicle will have plenty of traction in winter
conditions, even with the standard tyres. Nevertheless, we still recommend
that winter tyres or all-season tyres should be fitted on all four wheels when
winter road conditions are expected, mainly because this will give a better
braking response.
Snow chains
On roads where snow chains are mandatory, this also applies to cars with all-
wheel drive.
Changing tyres
On vehicles with all-wheel drive, all four tyres must have the same rolling
circumference ⇒page 242.
WARNING
•Even with all-wheel drive, you should always adjust your speed to suit
the conditions. Do not let the extra safety features tempt you into taking
any risks when driving. Failure to do so could result in an accident.
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Intelligent technology
190•The braking capability of your vehicle is limited by the tyres’ grip.
Vehicle behaviour is no different from a vehicle without four-wheel drive.
So do not be tempted to drive too fast on icy or slippery roads just because
the vehicle still has good acceleration in these conditions. Failure to do so
could result in an accident.•On wet roads bear in mind that the front wheels may start to aquaplane
and lose contact with the road if the vehi cle is driven too fast. If this should
happen, there will be no sudden increase in engine speed when aqua-
planing begins to warn the driver, as with a front-wheel drive vehicle. For
this reason and for that mentioned above, always choose a driving speed
suitable for the road conditions. Failure to do so could result in an
accident.
Brakes
What factors can have a negative effect on the brakes?New brake pads
New brake pads do not provide optimal performance during the first 400 km;
first they must be “run in”. However, the reduced braking capacity may be
compensated by pressing on the brake pedal a little harder. Avoid over-
loading the brakes during run-in.
Wear
T h e r a t e o f we a r o n t h e brake pads depends a great deal on how you drive and
the conditions in which the vehicle is operated. Negative factors are, for
instance, city traffic, frequent short trips or hard driving with abrupt starts
and stops. Wet roads or road salt
When the speed is
over 80 km/h and the windscreen wipers are on, the brake
system moves the pads towards the brake discs for a few seconds. This
occurs - without the driver knowing - at regular intervals and allows a faster
response from the brakes when driving on wet roads.
In certain conditions, such as in heavy rain, or after washing the vehicle or
driving through water, the full braking effect can be delayed by moisture (or
in winter by ice) on the discs and brake pads. In this case the brakes should
be dried by pressing the brake pedal several times.
The effectiveness of the brakes can also be temporarily reduced if the vehicle
is driven for some distance without using the brakes when there is a lot of salt
on the road in winter. In this case, the layer of salt on the brake discs and pads
has to wear off before braking.
Corrosion
There may be a tendency for corrosion to form on the discs and dirt to build
up on the brake pads if the vehicle is used infrequently or the brakes are not
used very often.
If the brakes are not used frequently, or if rust has formed on the disks, it is
advisable to clean off the pads and disks by braking firmly a few times at a
moderately high speed ⇒.
Faults in the brake system
If the brake pedal travel should ever increase suddenly, this may mean that
one of the two brake circuits has failed. Drive immediately to the nearest
specialised workshop and have the fault repaired. Drive there slowly and
remember that you will have to apply more pressure on the brake pedal and
allow for longer stopping distances.
Low brake fluid level
Malfunctions can occur in the brake system if the brake fluid level is too low.
The brake fluid level is monitored electronically.
WARNING (continued)
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