Seat belts169
Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
The physical principle of a frontal collision
The physical principle of a frontal a ccident can be explained quite simply:
Motion energy, so-called kinetic energy, is produced as soon as the vehicle is
moving, 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 and 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 acci-
dent.
The speed of the vehicle is, nevertheless,
the most important factor. Doubling the
speed of the vehicle from 25 km/h up to 50 km/hour increases the kinetic energy
four times.
The common opinion that it is possible to support your body in a minor accident
with your hands, is incorrect. Even in a collision at only a low speed, the forces
acting on the body are such that it is no longer possible to support your body.
Even if you only drive at a speed within the range from 30 km/hour to 50 km/hour,
the forces which are produced on your body in the event of an accident can easily
exceed 10.000 N (Newton). This equals a weight of one tonne (1 000 kg).
In the event of a frontal collision, occupants of the car not wearing a seat belt, are
thrown forward and strike in an uncontrolle d way parts of the interior of the car,
such as steering wheel, dash panel, windscreen, ⇒fig. 171 . The occupants of a
vehicle who have not fastened their seat belts may even be thrown out of the
vehicle. This can resu lt in fatal injuries.
It is also important that rear seat occupants fasten their seat belts as they will other-
wise be thrown through the vehicle in an uncontrolled manner in the event of an
accident A rear seat passenger who has not fastened the seat belt is a danger not
only to himself but also fo r those seated at the front ⇒fig. 172 .
Important safety information regarding the use of
seat belts
The correct use of the seat belts considerably reduces the risk of
injury!
WARNING
•The belt webbing must not be jammed in-between at any point or
twisted, or chafe against any sharp edges.
•It is important that the belt webbing is properly routed if the seat belts
are to offer their maximum protection ⇒page 170.
Fig. 171 The driver is thrown
forward if not wearing a belt
Fig. 172 The rear seat occu-
pant is thrown forward if not
wearing a belt
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Intelligent Technology
194
•when driving with snow chains
•when driving in deep snow or on a loose surface
•when it is necessary to rock a ca r free when it has become stuck.
then you should switch on the ESP again.
WARNING
It is also not possible for the ESP to overcome the physical limits of the
vehicle. 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 particularly applies when driving on slippery and wet roads. The
increased safety offered must not tempt you to take greater risks than other-
wise - risk of an accident!
Note
•All four wheels must be fitted with the same tyres in order to achieve problem-
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 other assign-
ment of tyres and wheels) can influence the function of the ESP ⇒page 243,
“Accessories, changes and replacement of parts”.
Electronic Differential Lock (EDS)*
The electronic differential lock pr events an individual wheel from
slipping.
Models fitted with ESP are equipped with electronic differential lock (EDL).
General
The EDL makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditio ns of the road surface are unfavourable. 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 sensors.
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 proces s 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.
WARNING
•Depress the accelerator carefully when accelerating on uniformly slip-
pery 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
surface 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
otherwise - risk of an accident!
Note
•If the ABS or ESP warning light comes on, this may also indicate a fault in the
EDL. Please have the car inspected as soon as possible by a specialist garage.
•Changes to vehicle (e.g. on engine, on the brakes, on chassis or other assign-
ment of tyres and wheels) can in fluence the function of the EDL ⇒page 243,
“Accessories, changes and replacement of parts”.
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Intelligent Technology195
Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
Traction control system (TCS)
The traction control system prevents the driven wheels from spinning
when accelerating.
General
The TCS makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditio ns of the road surface are unfavourable.
Operating principle
The TCS switches on automatically when th e 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 surface is
automatically adapted by redu cing the engine speed. This occurs at all speeds.
The TCS operates in combination with the ABS ⇒page 197, “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 37.
Switching off
You can switch the TCS off and on again as you wish by pressing the button
⇒ fig. 198 . The TCS warning light lights up in the instrument cluster when the TCS is
switched off
⇒ page 37. 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.
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 problem-
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 other assign-
ment of tyres and wheels) can in fluence the function of the TCS ⇒page 243,
“Accessories, changes and replacement of parts”.
Driver-steering recommendation*
The driver-steering recommendation is an additional function of the electronic
stability programme (ESP). This function indicates to the driver in critical situations
by means of slight steering wheel impulses the direction evaluated by the system,
in which the vehicle must be steered, so that it stabilizes. The driver-steering
recommendation is active when braking shar ply on different road surfaces and on
the right and left vehicle side.
Fig. 198 TCS switch
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Wheels and Tyres241
Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
•The wheel bolts must be clean and must turn easily. However, they must
never be treated with grease or oil.
•If the wheel bolts are tightened to a too low tightening torque, the rim
can lossen when the car is moving - risk of accident! A tightening torque
which is too high can damage the bolts and threads and this can result in
permanent deformation of the contact surfaces on the rims.
Caution
The prescribed tightening torque of the wheel bolts for steel and light alloy wheels
is 120 Nm.
Winter tyres
The handling of your vehicle will be significantly improved when driving on wintry
roads if you fit winter tyres. Summer tyres do not offer the same grip on ice, snow
and at temperatures below 7 °C because of their construction (width, rubber blend,
tread pattern). This partic ularly applies to vehicles which are equipped with low-
profile tyres or high-speed tyres (code index H or V on wall of tyre).
Winter tyres must be mounted on all four wheels to obtain the best handling char-
acteristics.
You must only fit those types of winter tyre which are approved for your vehicle. The
permissible sizes of winter tyres are stated in your vehicle documents. Approvals
may differ because of national legislation.
Please remember that the tyres should be in flated to 20 kPa (0.2 bar) more than is
the case for summer tyres ⇒page 237.
Winter tyres no longer offer the same winter performance once the tyre tread has
worn down to a depth of about 4 mm.
Ageing also causes winter tyres to lose most of their winter performance properties
- even in cases where the remaining tread depth is still clearly more than 4 mm.
Speed restrictions apply to winter tyres as well as to summer tyres ⇒page 239,
⇒ . You can fit winter tyres of a lower speed ca
tegory to your vehicle provided that you
also do not drive faster than the permissible maximum speed for such tyres, even
if the possible maximum speed of your vehicle is higher. The corresponding tyre
category can damage the tyres when exceeding the permissible maximum speed.
Please pay attention to the notes if you decide to fit winter tyres ⇒page 237.
You can also fit so-called “all-year tyres” instead of winter tyres.
Please contact your specialist garage if there are any points which are not clear who
will be able to provide you with information regarding the maximum speed for your
tyres.
WARNING
You must on no account drive your car at more than the permissible
maximum speed for your winter tyres - risk of an accident resulting from
tyre damage and loss of control over your car.
For the sake of the environment
Fit your summer tyres on again in good ti me since summer tyres offer you better
grip and handling on roads which are free of snow and ice as well as ar tempera-
tures below 7 °C - the braking distance is shorter, there is less tyre noise, tyre wear
is reduced and fuel consumption is reduced.
Note
Please observe the various differing legal requirements regarding tyres.
Unidirectional tyres*
The direction of rotation of the tyres is marked by arrows on the wall of the tyre.
This indicates the direction of rotation of the tyre, and it is essential that the tyres
are fitted on to run in this direction. Only then are the tyres able to provide the
optimal properties in terms of grip, lo w noise, wear-and-tear and aquaplaning.
Should it be necessary to fit on a spare wheel in exceptional cases with a tyre not
dedicated to the running dire ction or in opposite running direction, please adopt a
WARNING (continued)
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Breakdown assistance
256
Towing in a vehicle fitted with a manual gearbox
Please refer to the notes ⇒page 253.
The car can be towed in with a tow bar or a tow rope or with the front or rear wheels
raised. The maximum towing speed is 50 km/h.
Towing of a vehicle with an automatic gearbox
Please refer to the notes ⇒page 253.
The car can be towed in with a tow bar or a tow rope. Refer at the same time to the
following guidelines:
•Move selector lever into N .
•The maximum towing speed is 50 km/h.
•The maximum permissible towing distance is 50 km. The gear oil pump does
not operate when the engine is not runni ng; the gearbox would not be adequately
lubricated at higher speeds an d over longer towing distance.
Caution
If the vehicle is towed in by a recovery vehi cle, it should only be towed in with the
front wheels raised. If the vehicle is raised at rear, the automatic gearbox is
damaged! (Does not apply to the automatic gearbox DSG).
Note
The vehicle must be transported on a special ve hicle or trailer if it is not possible to
tow in the vehicle in the way described or if the towing distance is greater than
50 km.
Towing with four-wheel drive
Please refer to the notes ⇒page 253.
The car can be towed in using a tow bar or a tow rope or with the front axle raised. The maximum towing speed is 50 km/h
, the maximum permissible towing
distance is 50 km.
Note
The vehicle must be transported on a special vehicle or trailer if it is not possible to
tow in the vehicle in the way described or if the towing distance is greater than
50 km.
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