AUDI A4 2008 B8 / 4.G Owners Manual
Page 141 of 342
adaptive cruise control (ACC)139
An acoustic warning will also sound (unless it has been deacti-
vated in the sound system or MMI* settings).Note
Pressing the brake pedal will switch off the adaptive cruise
control system. The speed set at that point will, however, remain
stored until the adaptive cruise control is activated again.
To resume the programmed cruising speed, release the brake
pedal and pull the control lever towards you ⇒page 132,
“Switching off the system (with speed memory function) and reacti-
If you exceed the target speed by pressing the accelerator, the
driver intervention prompt will not be accompanied by a warning
tone. The indicator lamp shown in the display will also switch off
when the target speed is exceeded.
If the adaptive cruise control triggers a braking operation the
hydraulic brake system is under pressure. This is why brake pedal
travel will be shorter and the pedal will feel “harder”.
Applies to vehicles: with adaptive cruise controlSetting the warning tone volume and driving program
You can change the adaptive cruise control settings on
the sound system or MMI* to suit your individual driving
style.– Select: Function selector button > adaptive cruise
control.Setting the volume of the warning tone
If the adaptive cruise control system switches off (e.g. when the ESP
intervenes) or a driver intervention prompt appears, a warning tone
You can set the volume of the warning tone to low, medium, or high.
The new volume will sound briefly after making any adjustment. If
you do not want a tone to sound, select off.
Adjusting the basic settings
You can set the distance (time interval) you want the adaptive cruise
control system to keep to the vehicle in front by selecting distance
1, distance 2, distance 3 or distance 4.
Fig. 148 Display: adap-
tive cruise control
document_0900452a81b1b9de.book Seite 139 Donnerstag, 26. Juli 2007 9:16 09
Page 142 of 342
adaptive cruise control (ACC) 140Setting the driving program
In the Driving program menu you can select either dynamic,
standard or comfort according to your personal preferences.
We recommend you to leave the warning tone switched on. Even
when the warning tone is switched off, not every warning tone will
When you pass the key on to somebody else please remember to
make the other driver aware of the ACC settings.
We recommend a minimum distance setting of DISTANCE 3
(factory default setting).
When the ignition is switched off, the distance setting reverts to
the factory default DISTANCE 3. A qualified workshop can cancel
this function. In this case a default distance setting defined on the
sound system or MMI* is applied each time the engine is started.
System limitationsApplies to vehicles: with adaptive cruise controlGeneral notes
The following situations could impair the function of the
radar sensor.The adaptive cruise control is subject to given physical limits and
also has certain limits determined by the system itself. Under
certain circumstances the driver may feel that the ACC system is
responding unexpectedly or belatedly. For this reason, please
always give your full attention to road traffic and if necessary take
When driving through bends ⇒page 140.
When vehicles in front are not in line with your vehicle
When other vehicles change lanes ⇒page 141.
When other vehicles are not clearly discernible ⇒page 141
When vehicles are stationary ⇒page 142.
The radar sensor's "field of vision" can be impaired by rain, snow
or a lot of water on the road. This results in vehicles in front not
being properly recognised or, in some circumstances, not being
detected at all. If necessary, take action yourself!Applies to vehicles: with adaptive cruise controlWhen driving through bends
Fig. 149 Driving into a
bendFig. 150 Driving out of
document_0900452a81b1b9de.book Seite 140 Donnerstag, 26. Juli 2007 9:16 09
Page 143 of 342
adaptive cruise control (ACC)141
Technical data Driving into a bend
When you are driving into a bend, the ACC system may react to a
vehicle travelling in the other lane and therefore brake the vehicle
⇒page 140, fig. 149. You can override the braking effect by pressing
Driving out of a bend
When you are driving out of a long bend, the ACC system may - in
the course of its calculation of the lane ahead - react to a vehicle
travelling in the other lane and therefore brake the vehicle
⇒page 140, fig. 150. You can override the braking effect by pressing
Applies to vehicles: with adaptive cruise controlVehicles in front travelling out of lineVehicles in front which are not in line with your vehicle cannot be
detected by the ACC system until they are within the range of the
Applies to vehicles: with adaptive cruise controlOther vehicles changing lanesVehicles which are very close to you when they move onto your lane
cannot be detected by the radar sensor until they move into its
range.Applies to vehicles: with adaptive cruise controlNot clearly discernible vehiclesVehicles that are not clearly discernible, e.g. a motorcycle travelling
in front of you and vehicles with a large amount of ground clearance
or protruding freight, are often identified late or may not be
detected at all.
Fig. 151 The vehicle in
front is outside the
range of the radar
Fig. 152 A vehicle is
changing lanesFig. 153 Motorcycle in
document_0900452a81b1b9de.book Seite 141 Donnerstag, 26. Juli 2007 9:16 09
Page 144 of 342
adaptive cruise control (ACC) 142Applies to vehicles: with adaptive cruise controlStationary vehiclesIf a vehicle detected by the ACC system turns off or changes lane
and another stationary vehicle is located in front of that vehicle, the
ACC system will not react to the stationary vehicle ⇒fig. 154 and
Audi braking guardApplies to vehicles: with adaptive cruise controlDescription
Audi braking guard warns you in case of an impending
collision with a vehicle in front.Audi braking guard is active at speeds above approximately 30 km/h
and operates within the system limitations ⇒page 140 even when
the adaptive cruise control is deactivated.
The radar sensor is fitted at the front of the vehicle ⇒page 130,
fig. 137. The system requires reflecting surfaces in order to be able
to measure the distance. If the ACC is unable to measure the
distance it will not respond.
Once the system has measured the distance, it can assess a
dangerous situation where a vehicle in front brakes suddenly or you
are driving fast and approach a vehicle travelling at a much slower
speed. The system warns you as soon as it anticipates that a poten-
tial collision with the vehicle in front can only be avoided by hard
braking or by taking evasive action.
The system has a preset response time so that it can warn you in
time. In certain situations, the system response time will be reduced
dynamically, e.g. when you are accelerating onto a motorway.
Braking, lateral acceleration and steering angle are other factors
Fig. 154 Vehicle
turning off and vehicle
stationaryFig. 155 Vehicle
changing lane and
Fig. 156 Instrument
document_0900452a81b1b9de.book Seite 142 Donnerstag, 26. Juli 2007 9:16 09
Page 145 of 342
adaptive cruise control (ACC)143
Technical data which can shorten the system response time. The warning will be
deactivated if you press the accelerator pedal right down in order to
The system draws the driver's attention to two different hazardous
A distance warning will be given if you travel too close to the vehicle
in front for longer than 5 seconds. For example, if the distance is
less than 9 m at 80 km/h, a message will appear in the instrument
cluster display ⇒page 142, fig. 156.
If the vehicle in front were to brake hard, a collision would no longer
be avoidable, even if you reacted immediately. In this case, you
should leave more room between your car and the vehicle in front.
If the vehicle in front of you is travelling in the same lane at a much
slower speed or if it brakes hard, the Audi braking guard will calcu-
late the time at which a collision can be avoided only by emergency
braking or evasive action. When the system warns you, it is possible
to avoid a potential collision with the vehicle in front by braking or
changing lane. There are two warning levels:
Early warning: A message will appear in the instrument cluster
display and you will also hear a warning tone.
Acute warning: The second (acute) warning will be triggered if
you do not react to the advance warning. There will automatically be
a short dab of the brakes to remind you to concentrate on the traffic.
If you brake hard, the brake assist system ⇒page 222 helps you to
achieve the optimum braking effect.
Please always direct your full attention to the road, even when the
Audi braking guard is activated. It is always you who is responsible for determining your speed and for keeping a safe distance to the
other vehicles on the road.
Always maintain the statutory minimum safety distance to the
vehicle in front (risk of accident).
Due to the system limitations, the Audi braking guard will not
react in certain situations, for example when approaching a
stationary obstacle (such as the end of a traffic jam or a broken-
Please note that the Audi braking guard is subject to limita-
tions in tight bends on account of the radar sensor's field of vision.
This means that obstacles may not be detected in certain situa-
The radar sensor's "field of vision" can be impaired by rain,
snow or a lot of water on the road. This results in vehicles not
being reliably recognised or, in some circumstances, not being
detected at all. Always keep the road ahead within your field of
Reflecting objects, such as crash barriers or the entrance to a
tunnel, could impair the function of the radar sensor.
Applies to vehicles: with adaptive cruise controlStatus messages in the instrument cluster displaybraking guard brake jolt
This driver message appears when the brakes are dabbed due to an
braking guard off
This driver message appears when the system is switched off in the
MMI. The message also appears briefly after you begin driving if the
system is switched off.
document_0900452a81b1b9de.book Seite 143 Donnerstag, 26. Juli 2007 9:16 09
Page 146 of 342
adaptive cruise control (ACC) 144The message will also appear if the system is unavailable due to an
error or if you switch the ESP off ⇒page 222. In this state, the
system no longer warns you about an impending collision.Applies to vehicles: with adaptive cruise controlSettings for Audi braking guard
The system and warning settings can be adjusted via the
sound system or MMI*.– Select: Function selector button > Audi braking
System - The Audi braking guard system can be switched on and
Early warning - The acoustic signals and display messages can
be switched on and off.Note
The settings are stored on the remote control key in use. When you
pass the key on to somebody else please remember to make the
other driver aware of the Audi braking guard settings ⇒page 43.
Fig. 157 Display: Audi
document_0900452a81b1b9de.book Seite 144 Donnerstag, 26. Juli 2007 9:16 09
Page 147 of 342
Audi lane assist145
Audi lane assistAudi lane assistApplies to vehicles: with lane assistDescription
The lane assist system assists the driver in keeping the
vehicle in the right lane.The system uses a camera to detect the markings of the lane you are
driving in. If the vehicle approaches one of the detected lane mark-
ings, the steering wheel vibrates to warn the driver that the vehicle
might be about to cross one of the markings. The lane assist system
is functional when it has detected lane markings on both sides of
the lane you are driving in. The green lamp
in the instrument
cluster indicates that the function is activated and fully functional.
If you operate the turn signal before crossing one of the lane mark-
ings (while the lane assist system is functional), the system will
detect that the lane change is intended and will not warn the driver.
As the system is designed for driving on motorways and other major
roads, it is only active above a speed of about 65 km/h.
The lane assist system does not keep the vehicle in its lane. It
merely warns the driver when the vehicle is in danger of crossing
the markings of the lane. As the driver you are always responsible
for staying in your own lane.
The camera cannot detect all lane markings. Therefore it is
possible that variations in the road surface or objects might be
detected as lane markings, which can lead to false warnings, or
warnings not being given.
The camera's view might be obstructed, for example by vehi-
cles travelling in front, rain, snow, a lot of water on the road or adverse light. This can result in the system not detecting the lane
Applies to vehicles: with lane assistSwitching on and off– Press the button ⇒fig. 158 -arrow- to switch the system
on and off. The indicator lamp
in the instrument
cluster will light up or go out.
Fig. 158 Turn signal
lever: Pushbutton for
Audi lane assistFig. 159 Windscreen:
Camera window for
Audi lane assist
document_0900452a81b1b9de.book Seite 145 Donnerstag, 26. Juli 2007 9:16 09
Page 148 of 342
Audi lane assist 146Indicator lamp in instrument cluster Active: The green indicator lamp confirms that the system is fully
functional. You will be warned if you are about to cross the lane
markings detected by the system. Inactive: The yellow warning lamp indicates that the system is
switched on. However, you will not be warned if you cross the lane
markings. This can have the following causes:•
There is only one or no lane marking.
The system cannot detect the lane markings (e.g. due to snow,
dirt, wet conditions or adverse light).
There are more than two lane markings in the lane you are
driving in (e.g. in roadwork sections).
The vehicle's speed is below 65 km/h, the speed at which the lane
assist system is activated.
The lane is narrower than 2.5 m or wider than 5 m.
The bend is too tight.Note
Make sure that the camera window ⇒page 145, fig. 159 is not
covered with stickers or similar objects.
Always keep the camera window clean. Usually it should suffice
to operate the windscreen wipers.
Applies to vehicles: with lane assist and on-board computerInstrument cluster displayYou can call up the display for the lane assist by repeatedly pressing
the button on the windscreen wiper lever. For more details
refer to ⇒page 27.
When the lane assist is switched on, two lines indicate the lane
demarcations on the left and right of your vehicle.
Version : Monochrome display•
Solid red lines: The lane assist is switched on and ready to warn.
One red line flashing (left or right): The lane assist warns you
before you cross the lane demarcation ⇒fig. 160, A
Fig. 160 Instrument
cluster: lane assist
switched on and in
warning modeFig. 161 Instrument
cluster: lane assist
switched on but not
ready for warning
document_0900452a81b1b9de.book Seite 146 Donnerstag, 26. Juli 2007 9:16 09
Page 149 of 342
Audi lane assist147
Unfilled lines: The lane assist is switched on but not ready for
warning ⇒page 146, fig. 161,
Version : High-resolution display
Solid white lines: The lane assist is switched on and ready to
Solid red line (left or right): The lane assist warns you before you
cross the lane demarcation ⇒page 146, fig. 160.
Unfilled lines: The lane assist is switched on but not ready for
warning ⇒page 146, fig. 161.
Messages in the instrument cluster display
Should the lane assist be deactivated automatically, the indicator
lamp in the instrument cluster will go out and one of the following
messages will appear in the instrument cluster display:
Audi lane assist not available: currently no sensor vision
This message is displayed when the camera is no longer functional
after the system has continuously failed to detect the lane mark-
ings. This can have the following causes:
The outside of the camera window ⇒page 145, fig. 159 is dirty
or frosted. Please remove dirt or ice from this area of the wind-
The inside of the camera window is misted up. In this case,
please wait for the camera window to demist before switching on
the lane assist system again.
Due to the conditions (e.g. snow-covered road) the system has
not been able to detect the lane markings for a long period. Do not
switch the lane assist system on again before the lane markings are
Audi lane assist currently not available
A temporary error is preventing the lane assist system from fully
functioning. Try switching on the lane assist system again later.
Audi lane assist: system faultThe system should be checked by an Audi dealership or other qual-
Applies to vehicles: with lane assistSetting the warning time and steering vibration
You can change the lane assist settings on the sound
system or MMI* to suit your individual preferences.– Select: Function selector button > Audi lane assist.Setting time of warning
early: In this setting, the driver will be warned before a wheel
crosses a lane marking. The warning depends on the angle with
which the vehicle is approaching the lane marking. The larger the
angle with which you are driving towards the marking, the earlier
you will receive the warning, i.e. the distance between the vehicle
and the marking might still be still relatively long. If you are driving
toward the marking at a very narrow angle, you will receive the
warning later, i.e. shortly before one of the wheels touches the
adaptive: In this setting, the time of warning is adapted to the road
layout and the vehicle's speed. The warning will be received later
when you are driving through a bend, and earlier when you are
Fig. 162 Display:
Setting time of
warning and steering
document_0900452a81b1b9de.book Seite 147 Donnerstag, 26. Juli 2007 9:16 09
Page 150 of 342
Audi lane assist 148driving on a straight section. On narrow roads, the system will give
off warnings later than on wide roads.
late: In this setting, the driver will be warned when a wheel crosses
a lane marking.
Setting steering wheel vibration
You can set the steering vibration to low, medium or strong. The
steering wheel will vibrate so that you can check your selection.
The lane assist is not active while you are changing the setting;
the brief vibration of the steering wheel is only intended to help you
make the desired setting.
Your personal settings are stored automatically and assigned to
the remote control key which is being used.
document_0900452a81b1b9de.book Seite 148 Donnerstag, 26. Juli 2007 9:16 09