2013 AUDI S8 wheel

How knee airbags work
The risk of injury to the leg area con be re­
duced by fully inflated knee airbags.
Fig. 170 Inflated airbags protecting in a fro ntal coll i­
sio n
The knee airbag system has been designed so
that the airbags for the driver and front pas­
senger deploy in certain but not all frontal
collisions .
If the front airbags deploy, the knee airbags
also deploy in frontal collisions when the de­
ployment threshold stored in the control unit
is met .
When the system deploys, the airbags fill
with a propellant gas, and inflate between the
lower part of the instrument panel and the
driver and the lower part of the instrument
panel and the front passenger~
page 161,
fig . 167.
Although they are not a soft pillow, they can
"cush ion" the impact and in this way they can
help to reduce the risk of injury to the lower
extremities.
All of this takes place in the blink of an eye, so
fast that many people don't even realize that
the airbags have deployed . The airbags also
inflate with a great deal of force and it is im­
portant for occupant safety that nothing
should be in their way when they deploy.
Fully inflated airbags in combination with
properly worn safety belts slow down and lim­
it the occupant's forward movement and help
to reduce the risk of injury.
Airbag system 169
Important safety instructions on the
knee airbag system
Airbags ore only supplemental restraints . Al­
ways wear safety belts correctly and ride in a
proper seating position .
There is a lot that you and your passengers
must know and do to help the safety belts and
airbags to provide supplemental protection.
_& WARNING
An inflating knee airbag can cause serious injury. Wearing safety belts incorrectly and
improper seating positions increase the
risk of serious personal injury and death
whenever a vehicle is being used.
- The knee airbag system cannot protect
you properly if you a re seated too close
to any of the airbag locations. When ad­
justing their seat positions, it is impor­
tant that both the driver and the front
passenger keep their upper bodies and
knees at the following minimum safe
distances:
- at least 10 inches (25 cm) between the
chest and the steering wheel/instru­
ment panel.
- at least 4 inches (10 cm) between the
knees and the lower part of the instru­
ment panel.
- The risk of personal injury increases if
you lean forward or to the side, or if the
seat is improperly positioned and you are not wearing your safety belt. The risk in­
creases even more should the airbag de­ ploy.
- Always make sure that the knee airbag
can inflate without interference. Objects
between you and the airbag can increase
the risk of injury in an accident by inter­
fering with the way the airbag deploys or
by being pushed into you as the airbag
deploys.
- Never let anybody, especially children
or animals ride in the footwell in front

-Always install rear-facing child safety
seats on the rear seat.
- If you must install a rearward facing
child safety seat on the front passenger
seat in exceptional circumstances and
the
PASSENGER AIR BAG OFF light does
not come on and stay on, immediately
install the rear-facing child safety seat in
a rear seating position and have the air­
bag system inspected immediately by
your Audi dealer.
_& WARNING
If, in exceptional circumstances, you must
install a forward-facing child restraint on
the front passenger's seat:
- Always make sure the forward-facing
seat has been designed and certified by its manufacturer for use on a front seat
with a passenger front and side airbag.
- Always follow the manufacturer's in­
structions provided with the child safety
seat or carrier.
- Always move the passenger seat into its
rearmost position in the seat's fore and
aft adjustment range, as far away from
the airbag as possible before installing
the child restraint. The backrest must be
adjusted to an upright position .
- Always make sure that the
PASSENGER
AIR BAG OFF
light comes on and stays
on all the time whenever the ignition is
switched on.
(D Tips
Always replace child restraints that were
installed in a vehicle during a crash. Dam­
age to a child restraint that is not visible
could cause it to fail in another collision
situation.
Advanced front airbag system and children
Your vehicle is equipped with a front "Ad­
vanced Airbag System" in compliance with United States Federal Motor Vehicle Safety
Child Safety 177
Standard (FMVSS) 208 as applicable at the
time your vehicle was manufactured.
The Advanced Airbag system in your vehicle
has been certified to meet the "low-risk" re­
quirements for 3- and 6-year old children on
the passenger side and small adults on the driver side. The low risk deployment criteria
are intended to reduce the risk of injury
through interaction with the airbag that can
occur, for example, by being too close to the
steering wheel and instrument panel when
the airbag inflates . In addition, the system
has been certified to comply with the "sup­
pression" requirements of the Safety Stand­
ard, to turn off the front airbag for infants up
to 12 months who are restrained on the front
passenger seat in child restraints that are list­
ed in the Standard.
Even though your vehicle is equipped with an
Advanced Airbag system, all children, espe­ cially those 12 years and younger, should al­
ways ride in the back seat properly restrained
for their age and size. The airbag on the pas­
senger side makes the front seat a potentially dangerous place for a child to ride . The front
seat is not the safest place for a child in a for­
ward-facing child safety seat. It can be a very
dangerous place for an infant or a larger child
in a rearward-facing seat .
Advanced Airbags and the weight­
sensing mat in the front seat
The Advanced Airbag System in your vehicle
detects the presence of an infant or child in a
child restraint on the front passenger seat us­
ing the weight -sensing mat in the seat cush­
ion and the sensor below the safety belt latch
on the front passenger seat that measures the
tension on the safety belt.
The weight -sensing mat measures total
weight of the child and the child safety seat
and a child blanket on the front passenger seat. The weight on the front passenger seat
is related to the design of the child restraint
and its "footprint", the size and shape of the
bottom of the child restraint as it sits on the ..,.
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198 Intellige nt tec hno logy
Intelligent technology
Notice about data
recorded by veh ic le
control modules
Your vehicle is not equipped with an Event Da­
ta Recorder (EDR), installed by some manu­
facturers fo r the express purpose of capturing
data for retrieval after an accident or crash
event . EDR's are sometimes called "crash re­
corders".
Some state laws restrict the retrieval or down­
loading of data stored by EDR's that were in­
stalled in a vehicle for the express purpose of
retrieving data after an accident or crash
event without the owner's consent.
A lthough your vehicle is not equipped with an
EDR, it is equipped with a number of electron­
ic control modules for various vehicle systems
such as, for example, engine function, emis­
sion control, as well as for the airbags and
safety belts.
These electronic control modules also record
vehicle-related data during normal vehicle op­
eration for diagnostic and repair purposes.
The recording capacity of the electronic con­
trol modules is limited to data (no sound is re­
corded) and only a small amount of data is ac­
tually recorded over a very limited period of
time and stored when a system fault or other
condition is sensed by a control unit. Some of
the data then stored may relate to vehicle
speed, direction, braking as well as restraint
system use and performance in the event of a
crash or other condition. Stored data can only
be read and downloaded with special equip­
ment.
Electronic Stab ilization
Control (ESC)
Description
ESC helps to improve road holding and vehicle
dynamics to help reduce the probability of
skidding and loss of vehicle control. It works
only when the engine is running. ESC detects certain difficult driving situations, including
when the vehicle is beginning to spin (yaw)
out of control and helps you to get the vehicle back under control by selectively braking the
wheels, and/or reducing engine power and
providing steering assistance to help hold the
vehicle on the driver's intended course. The in­
dicator light
G) in the instrument cluster
blinks when ESC is taking action to help you
control the vehicle.
ESC has limitations.
It is important to remem­
ber that ESC cannot overcome the laws of
physics. It will not always be able to help out
under a ll cond itions you may come up against.
For example, ESC may not always be able to
help you master situations where there is a
sudden change in the coefficient of friction of
the road surface. When there is a section of
dry road that is suddenly covered with water,
slush or snow, ESC cannot perform the same
way it would on the dry surface . If the vehicle
hydroplanes (rides on a cushion of water in­
stead of the road surface), ESC will not be
able to help you steer the vehicle because con­
tact with the pavement has been interrupted
and the vehicle cannot be braked or steered.
During fast cornering, particularly on winding
roads, ESC cannot always deal as effectively
with difficult driving situations than at lower
speeds. When towing a trailer, ESC is not able
to help you regain control as it would if you
were not towing a trailer.
Always adjust your speed and driving style to road, traffic; and weather conditions. ESC can­
not override the vehicle's physical limits, in­
crease the available traction, or keep a vehicle
on the road if road departure is a result of
driver inattent ion. Instead, ESC improves the
possibility of keeping the vehicle under con­
trol and on the road during extreme maneu­
vers by using the driver's steering inputs to
help keep the vehicle going in the intended di­
rection . If you are traveling at a speed that
causes you to run off the road before ESC can
provide any assistance, you may not experi­
ence the benefits of ESC.

ESC includes and/or works together with the
anti-lock braking system (ABS), brake assist
system, anti-s lip regulat ion (ASR), electronic
d ifferential lock (EDL), dynamic steering* and
electronic interaxle differential lock*. ESC is
sw itched on all the time . In certain s ituations
when you need less tract ion, you can sw itch
off ASR by pressing the button above
~ page 200, fig. 188 the se lector lever. Be
sure to sw itch ASR o n aga in when yo u no lon­
ger need less traction.
Anti -lock braking system (ABS)
ABS prevents the wheels from locking up
when braking. The veh icle can still be steered
even du ring ha rd b raking . Apply steady p res­
sure to the brake pedal. Do not p ump the ped­
a l. A pulsing in the brake peda l indicates that
the system is he lping you to brake the vehicle .
Brake as sist system
The brake assist system can decrease bra king
d istance.
It increases braking power when the
driver presses the brake pedal qu ick ly in eme r­
gency situations . You must p ress and ho ld the
brake peda l until the situation is over. In
vehicles with adaptive cruise control*, the
brake assist system is more sensit ive if the
d istance detected to the vehicle ahead is too
small.
Anti- slip regulati on (A SR )
ASR reduces engine power when the drive
wheels begin to spin and adapts the force to the road condit ions. This makes it eas ier to
start, accelerate and drive up hills.
Electronic diff erential lo ck (EDL )
The ED L brakes wheels that are spinning and
transfers the drive power to the other drive
wheel or whee ls if the vehicle is equipped with
all whee l drive*. This funct ion is available up
to about 75 mph (120 km/h).
In extreme cases, EDL automatica lly switches
off to help keep the brake on the braked whee l
from overheating. EDL w ill switch on again au­
tomatically when conditions have returned to normal.
Int ellig ent technolog y 199
Dynamic ste ering *
On vehicles with dynam ic steering, ESC helps
stabilize the steering in certain situations.
Electronic intera xle differential l ock
function*
T he electron ic i nteraxle differential lock f unc ­
tion activa tes when dr iving th ro ugh curves.
Braking is targeted toward the wheels on the
inside of the curve as needed. This he lps to
minimize front whee l skid, improves traction
and allows for more precise driving through curves .
A WARNING
- ESC, ABS, ASR, EDL, dynamic steering*
and the elect ronic interaxle differential
loc k function* cannot ove rcome the laws
of physics. This is espec ially important
on slippery or we t roads.
If the systems
begin acting to stabilize your veh icle, you
should immediately change yo ur speed
to match the road and traffic conditions .
Do not let the increased safety provided
by these systems tempt you to take risks.
Doing so will increase the risk of a loss of
veh icle contro l, collision and ser ious per­
sonal injur ies.
- Always adapt your speed to road, traffic and weather conditions. The risk of los­ing con trol of the vehicle increases when
driving too fast, espe cially through
curves a nd on slippe ry or wet roads, and
when dr iving too close to vehicles up
ahead. ESC, ABS, the brake assist sys­
tem, EDL, ASR, dynam ic steering* and
the electron ic interaxle d ifferential lock
function" cannot prevent co llisions.
- Always accelerate with spec ial care on
even, smooth surfaces such as those that
are wet or covered with ice and snow.
The drive wheels can spin even w ith
these assistance systems that cannot al­
ways he lp to red uce the risk of loss of ve­
hicle control.
-
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200 Intelligent technology
-ABS and ASR on ly work correctly when
all four wheels are equipped w ith ident i­
ca l tires. Different tire s izes can lead to a
reduction in engine power.
- You may hear noises when the systems described are working.
- If the indicator light
DJ or m:11 (USA
models) ;tiJ (Canada models) appears,
there may be a malfunct ion
c::;, page 19,
c::;, page 18 .
Switching on and off
ESC turns on automatically when you start
the engine.
Fig. 188 Center console w ith ESC OFF button
Switching ASR off (sport mode)
In certain situat io ns, you can switch ASR and
ESC into sport mode by pressing the button
l!l
c::;, fig. 188. The indicator light II comes on
and the mess age Stabilization control (ESC ):
Off warning! Reduced stability appears. ASR
deactivates completely and the assistance provided by the ESC system is limited. Switch
to sport mode on ly when your driving skills,
traffic and weather cond itions permit .
I n some situations, it may be useful to switc h
ASR off to let the wheels slip. Example:
- Rocking the vehicle back and forth when it is
stuck
- Driving in deep snow or on loose ground
- Driving with snow cha ins
Switching ASR on Press the button[!] aga in. The message Stabi­
lization control (ESC): On appears.
A WARNING
- Drive whee ls can sp in and you can lose
control of the vehicle more eas ily when
ASR and ESC are in sport mode, especial­
ly when the road is slippery.
- Sw itch to sport mode only when your
driving skills, traff ic and weather condi­
tions permit.
@ Tips
You cannot sw itch sport mode on when
adaptive c ruise control* is working.
Braking
General information
What affects braking efficiency?
-
Operating conditions and driving habits
The brakes on today's automobiles are still
subject to wear, depending largely on operat­
ing condit ions and driving habits
c::;, &. . On
vehicles that are either dr iven mostly in stop­
and-go city traffic or are driven hard, the
brake pads should be checked by your author­
ized Audi dea ler more often than specified in
the Warranty
& Maintenance booklet. Failure
to have your brake pads inspected can result
in reduced brake performance.
On steep slopes, you should use the braking
effect of the engine. This way, you prevent un­
necessary wear on the brake system. If you
must use your brakes, do not hold the brakes
down continuously. Pump the brakes at inter­
vals .
Operating noise
Noises may occur when braking depending on
the speed, braking force and outside condi­
tions such as temperature and humidity.
Due to the nature of the materia ls used in ce­
ramic brake rotors*, noises may become more
apparent at low speeds. .,..

Effect of w ate r and ro ad sa lt
In certain situa tions, for example after driving
through water, in heavy rain, after overnight
condensation or after washing your car, the
braking effect can be reduced by moisture or
ice on the brake rotors and brake pads. The
brakes must be dried first wit h a few careful
brake applications.
At higher speeds and with the windshield wip ­
ers turned on, the brake pads press against
the brake rotors for a short amount of time.
This occurs at regular intervals w ithout the
driver noticing and provides for better brake response time under wet condit ions.
The effectiveness of the brakes can be reduced
when the vehicle is dr iven o n a salt-covered
road and the brakes are not used . Likewise,
you clean
off accumulated sa lt coating from
brake discs and pads with a few caut ious ap­
p lications of the brake¢&. -
Due to their surface characteristics, ceram ic
brake roto rs* absorb mo isture in such condi­
tions. This can cause a temporary reduction in
b rak ing fo rce compared to d ry brakes. You can
compensate for this by pressing the brake pedal harder .
Corrosion
There may be a tendency for dirt to build up
on the brake pads and corrosion to form on
the discs if the car is not dr iven regularly or
on ly for short t rips with little use of the
brakes.
I f t he b rakes are not used frequently, or if co r­
rosion has formed on the dis cs, it is advisable
to clean
off the pads and discs by brak ing
firm ly a few times from a moderately high
speed ¢.&. .
Faults in the brake system
If you should notice a sudden increase in
b rake peda l travel, then o ne of the two bra ke
circuits may have failed~ .&..
Int ellig ent technolog y 201
Low br ake fluid level
Malfunctions can occu r in the bra ke system if
the b rake fluid level is too low. The brake fluid
level is monitored electronica lly.
Brake lining wear status
B rake lining wear may be checked by visual in­
spe ct ion of the condition of the brake pads
through the open ings in the wheel. If neces­
sary, the whee l may be removed for this in­
spection
r=;, page 2 7 3, Changing a wheel.
_& WARNING
-You should perform braking maneuvers
for the purpose of cleaning the brake
system only if road conditions permit.
Other road users must not be put at risk -
you may cause an accident!
- Before descend ing a steep grade, reduce
speed and sh ift transmission into a lower
gear or lower dr iving range . Do not ride
the brakes or hold t he pedal down too
long o r too often. Th is could cause the
brakes to get hot and diminish braking
efficiency .
- Do not "ride the brakes" by rest ing you r
foo t on the pedal when you do not intend
to b rake . This may cause the brakes to
overheat, premature wear and increased
stopping distance.
- Under certain climatic and operating
conditions such as passing thro ugh wa­
ter, dr iv ing in heavy rain or after washing
the vehicle, the effectiveness of the brakes can be reduced. In winter, ice can
accumu late on the brake pads, lin ings,
discs and drums . Carefully app ly brakes
for a test. Brakes w ill dry and ice coat­
ings w ill be cleaned
off after a few care­
fu l brake applicat ions.
- Driving for an extended period of time on
salt- cove red roads without using your
brakes can a lso affect braking efficiency .
Clean
off accum ulated salt coating from
brake discs and pads with a few careful
brake applications.
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202 Intellig ent technol ogy
- If you damage the fro nt spoiler, or if you
install a different spoiler, be sure the air
flow to the front brakes is not obstruct­ ed . Otherwise the brake system could
overheat reducing the effectiveness of
the ent ire brake system .
- Failure of one brake c ircuit will impair
the braking capability resulting in an in­ creased stopp ing distance. Avoid driv ing
the vehicle and have it towed to the near­ est Aud i dea ler or qualified workshop .
Brake booster
The brake booster adds extra braking power .
The brake booster works with vacuum pres­
sure which is created only when the engine is
running ¢& .
& WARNING
-Never let the vehicle ro ll to a stop w ith
the engine shut off.
- If the brake booster is not work ing, for
example when towing your vehicle, or
because the b rake booste r has somehow
been damaged, the brake pedal must be
pressed considerab ly harder to make up
for the lack of booster assistance .
Servotronic® -
advanced power
steering system
The power steering systems use the power of
the running engine to allow precise steering
with little effort.
The advanced Servotronic ® power steering
system senses the road speed and e lectroni­
cally adjusts powe r ass istance to p rov ide com ­
fortable and sa fe stee ring response exactly
matc hed to the ve hicle speed .
Power steering w il l not work if the eng ine is
off . As a result, the steering whee l w ill be hard
to turn.
The power steering fluid level is chec ked dur­
ing the scheduled ma intenance serv ices.
(D Note
If there is an e lectronic malfunction, ser­
votronic
will still function like a conven­
tiona l power steering system, providing a
constant steering support force that is no
l onger proportionate to the vehicle speed.
This is most not iceable when t urning the
steering wheel at low speeds (for example
when pa rking), - more effort w ill be re­
q uired than us ual.
- Be aware of the diffe rent than usual
steering response and adjust your steer­
ing force acco rding ly.
- Have the problem checked and set right
by an A udi dealer as soon as poss ible.
(D Tips
- When the eng ine is running, never ho ld
the stee ring wheel turned all the way to
the rig ht or to the left fo r longer than 15
seconds. The powe r stee ring pump will
overheat the hydraulic fluid i f yo u keep
holding the stee ring wheel turned all the
way. This is likely to damage the power steering system.
- If the powe r steering system sho uld fai l
entire ly, or if the engine is not runn ing
(for example, wh ile be ing towed), you
w ill still be able to stee r the veh icle.
However,
considerably more effort will
be requi red to do so.
- If the power steering system should
have a leak, or is not functioning proper­
ly, contact your author ized Audi dealer
immed iately.
- The power steer ing system req uires a
specially fo rmu lated hyd raulic fluid. The
powe r stee ring fluid reservoir is located
in the engine comp art ment¢
page 234.
T he cor rect fluid level in the reservoir is
impo rtant fo r proper functioning of the
powe r stee ring .

Driving with your
quattro ®
With All Wheel Drive, all four wheels are driv­
en .
Gene ral inform ation
W ith All Whee l Drive, power is distributed to
all four wheels . This happens automatically
depending on your driving style and the road
conditions at the t ime. See also
t::;> page 198.
W ith the spo rt differential*, power d istribu­
tion to the rear wheels is variable and can be
adj usted with Aud i drive select*
t::;> page 109.
Always read and fo llow safety precautions
c:> .&. .
Winter t ires
When driving in the winter , your vehicle with
All Wheel Dr ive has an advantage, even with
regular t ires. In winter road conditions it may
be advisable to mount winter tires (or all-sea­
son tires) for improved driveability and brak­ ing: these tires must be mounted on
a ll four
w he els .
See also c:> page 264, Winter tires.
Sn ow cha ins
Where snow cha ins a re mandatory on certa in
roads, th is normally a lso applies to vehicles
with A ll Wheel Drive
c:> page 265, Snow
chains .
Replacing whe els/ tires
Vehicles w ith All Whee l Dr ive must always
have tires of the same size. Also avoid t ires
with different tread depths. For details see
page
c:> page 260, New tires and replacing
tires and wheels .
Off-Road driving?
Your Audi does not have enough ground clear­
ance to be used as an off-road vehicle.
It is
therefore best to avoid rough tracks and un ­
even terrain as much as possible. Also refer to
c:> page207.
Int ellig ent technolog y 203
A WARNING
Always adjust your driv ing to road and traf­
fic conditions. Do not let the extra safety
afforded by All Wheel Dr ive tempt you into
taking extra risks .
- Although the All Wheel Drive is very ef­
fective, always remember that braking capacity is lim ited by tire t raction. You
should therefore not d rive at excessive
speeds on icy or slippery road surfaces.
- On wet road surfaces, be careful not to
drive too fast because the fron t wheels
could begin to slide on top of the water (aquaplaning) . If this should occur, yo u
will have no warning from a s udden in­
crease in engine speed as w ith a front­
wheel drive veh icle. Always drive at
speeds which are su ited to the road con­
ditions - risk of crash.
Energy management
Starting ability is optimized
Energy management controls the distribution
of electrical energy and thus optimizes the
availability of electrical energy for starting
the engine .
If a vehicle with a conve ntiona l energy system
is not drive n for a long per iod of t ime, the bat­
tery is discharged by idling current consume rs
(e.g . immobilizer). In certain circumstances it
can resu lt in the re being insuff icient energy
available to start the engine.
Intelligent energy management in your vehi­
cle handles the distribution of e lectrica l ener­
gy. Starting ability is marked ly improved and
the life of the battery is extended.
Basica lly, energy management consists of
b atte ry diagno sis, i dling current man age­
ment
and d y namic ene rg y management .
Battery diagno sis
Battery diagnosis continuously determines
the sta te of the battery. Sensors determine
battery voltage, battery current and battery
Ii),,
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