182Driving and operatingBy pressing m to activate cruise
control or adaptive cruise control or
by switching off the ignition, speed
limiter is also deactivated and the
stored speed is deleted.
Adaptive cruise control Adaptive cruise control is an
enhancement to traditional cruise
control with the additional feature of
maintaining a certain distance behind
the vehicle ahead.
Adaptive cruise control automatically
decelerates the vehicle when
approaching a slower moving vehicle. It then adjusts the vehicle speed to
follow the vehicle ahead at the
selected following distance. The
vehicle speed increases or decreases to follow the vehicle in front, but willnot exceed the set speed. It may
apply limited braking with activated
brake lights.
The adaptive cruise control can store
and maintain speeds over approx.
50 km/h and brakes automatically to
follow a slower vehicle driving ahead
down to a minimum speed of
30 km/h.
Adaptive cruise control uses a radar sensor to detect the vehicles ahead.
If no vehicle is detected in the driving path, the adaptive cruise control will
behave like a traditional cruise
control.
For safety reasons, the system
cannot be activated before the brake
pedal has been depressed once after
switching on ignition. Activation in first gear is not possible.
Adaptive cruise control is mainly
advised to be used on long straight
roads, e.g. highways or country roads
with steady traffic. Do not use the
system if it is not advisable to
maintain a constant speed.
Control indicator A 3 116, m 3 116.
9 Warning
The complete driver attention is
always required while driving with adaptive cruise control. The driver stays fully in control of the vehicle
because the brake pedal, the
accelerator pedal and the cancel
switch have priority over any
adaptive cruise control operation.
Switching on
Press C to switch on adaptive cruise
control. The control indicator m
illuminates white.
Driving and operating183Activation by setting the speed
Adaptive cruise control can be
activated between 50 km/h and
180 km/h.
Accelerate to the desired speed and
turn thumb wheel to SET/-; the
current speed is stored and
maintained. Control indicator m
illuminates green.
The adaptive cruise control symbol,
the following distance setting and set
speed are indicated in the top line ofthe Driver Information Centre.
The accelerator pedal can be
released. Adaptive cruise control
remains activated while gearshifting.
Overriding set speed
It is always possible to drive faster
than the selected set speed by
depressing the accelerator pedal. When the accelerator pedal is
released, the vehicle returns to the
desired distance if a slower vehicle is
ahead. Otherwise it returns to the
stored speed.
Once the system is activated,
adaptive cruise control decelerates or
brakes if it detects a vehicle ahead
which is slower or closer than the
desired following distance.
9 Warning
Accelerating by the driver
deactivates automatic braking by
the system. This is indicated as a
pop-up warning in the Driver
Information Centre.
Increase speed
With adaptive cruise control active,
hold thumb wheel turned to RES/+:
speed increases continuously in large
increments, or activate RES/+
repeatedly: speed increases in small increments.
With adaptive cruise control active, if
the vehicle is driven much faster than the desired speed, e.g. after
depressing the accelerator pedal,
then the current speed can be stored
and maintained by turning the thumb
wheel to SET/-.
Reduce speed With adaptive cruise control active,hold thumb wheel turned to SET/-:
speed decreases continuously in
Driving and operating1859Warning
The driver accepts full
responsibility for the appropriate
following distance based on traffic, weather and visibility conditions.
Following distance must be
adjusted or the system switched
off when required by the prevailing
conditions.
Detecting the vehicle ahead
The green illuminated "vehicle
ahead" control indicator A is
displayed in the speedometer when the system detects a vehicle in the
driving path.
If this symbol does not appear, or
appears briefly, adaptive cruise
control will not respond to vehicles
ahead.
Deactivation
Adaptive cruise control is deactivated by the driver when:
● y is pressed.
● Brake pedal is applied.
● Clutch pedal is depressed for more than four seconds.
● Gear selector lever of automatic transmission is moved to N.
The system is also automatically deactivated when:
● Vehicle speed slows down below
45 km/h or accelerates above
190 km/h.
● Traction Control system is operating for more than
20 seconds.● Electronic Stability Control is operating.
● There is no traffic and nothing detected on the road sides forseveral minutes. In this case
there are no radar echoes and
the sensor may report that it is
blocked.
● Collision imminent braking system is applying the brakes.
● Radar sensor is blocked by an ice
or water film.
● A fault is detected in the radar, engine or brake system.
When adaptive cruise control is
deactivated automatically, the control indicator m illuminates white and a
warning symbol is displayed as a pop- up in the Driver Information Centre.
186Driving and operating
The stored speed is maintained.
9Warning
When adaptive cruise control is
deactivated, the driver must take
over full brake and engine control.
Switching off
Press C to switch off adaptive cruise
control. The control indicator m
extinguishes. The stored speed is
deleted.
Switching off the ignition also
switches off adaptive cruise control
and deletes the stored speed.
Driver's attention
● Use adaptive cruise control carefully on bends or mountain
roads, as it can lose the vehicle
ahead and require time to detect
it again.
● Do not use the system on slippery roads as it can create
rapid changes in tyre traction
(wheel spinning), so that you
could lose control.
● Do not use adaptive cruise control during rain, snow or
heavy dirt, as the radar sensor
can be covered by a water film,
dust, ice or snow. This reduces or completely suppresses the
visibility. In case of sensor
blockage, clean the sensor
cover.
System limits ● The system's automatic brake force does not permit hard
braking and the braking level
may not be sufficient to avoid a
collision.● After a sudden lane change, the system needs a certain time to
detect the next preceding
vehicle. So if a new vehicle is
detected, the system may
accelerate instead of braking.
● Adaptive cruise control does ignore the oncoming traffic.
● Adaptive cruise control does not brake for stopped vehicles,
pedestrians or animals.
Bends
The adaptive cruise control calculates
a predicted path based on the
centrifugal force. This predicted path
considers the current bend
characteristic, but cannot consider a
future bend change. The system may lose the current vehicle ahead or
consider a vehicle which is not in the
actual lane. This can happen when
Driving and operating187entering or exiting a bend or if the
bend gets stronger or weaker. If it no
longer detects any vehicle ahead,
then control indicator A will
extinguish.
If the centrifugal force is too high in a
bend, the system slows down the vehicle slightly. This braking level is
not designed to avoid spinning off the bend. The driver is responsible for
reducing the selected speed before
entering a bend and in general to
adapt the speed to the road type and
to existing speed limits.
Motorways
On motorways, adapt the set speed
to the situation and the weather.
Always consider that adaptive cruise
control has a limited visibility range, a
limited braking level and a certain
reaction time to verify if a vehicle is in
the driving path or not. Adaptive
cruise control may not be able to
brake the vehicle in time to avoid a
collision with a much slower vehicle or after a lane change. This is
particularly true if driving fast or if the
visibility is reduced due to weather
conditions.
While entering or exiting a motorway,
adaptive cruise control may lose the
vehicle ahead and accelerate up to
the set speed. For this reason,
decrease the set speed before the
exit or before the entry.
Vehicle path changes
If another vehicle enters your driving
path, adaptive cruise control will first
consider the vehicle when it is
completely in your path. Be ready to
take action and depress the brake
pedal, if you need to brake more
quickly.
Hill and trailer considerations
System performance on hills and
when towing a trailer depends on
vehicle speed, vehicle load, traffic
conditions and the road gradient. It
may not detect a vehicle in your path
while driving on hills. On steep hills,
you may have to use the accelerator
pedal to maintain your vehicle speed.
When going downhill, especially
when towing a trailer, you may have
to brake to maintain or reduce your
speed.
Note that applying the brake
deactivates the system. It is not
recommended to use adaptive cruise
control on steep hills especially when towing a trailer.
190Driving and operating
Note that the alert timing sensitivity
setting is shared with the following distance setting of the adaptive cruise control. So changing the alert timing
sensitivity changes the adaptive
cruise control following distance
setting.
Alerting the driver
A green illuminated vehicle ahead
control indicator A illuminates in the
instrument cluster when the system has detected a vehicle in the driving
path. When the distance to a
preceding moving vehicle gets too
small or when approaching another
vehicle too rapidly and a collision is
imminent, the collision alert symbol
pops-up in the Driver Information
Centre. Simultaneously a warning
chime sounds.
Depress the brake pedal, if it is
required by the situation.
Settings
Settings can be changed in the Auto
collision preparation menu in the
vehicle personalisation 3 129.
Forward collision alert based on
front camera system
Forward collision alert uses the front
camera system in the windscreen to
detect a vehicle directly ahead, in
your path, within a distance of approx.
60 metres.
Activation
Forward collision alert operates
automatically above 40 km/h, if it is
not deactivated by pressing V, see
below.
Selecting the alert sensitivity
The alert sensitivity can be set to
near, medium or far.
Driving and operating191
Press V; the current setting is shown
in the Driver Information Centre.
Press V again to change the alert
sensitivity.
Alerting the driver
A green illuminated vehicle ahead
control indicator A illuminates in the
instrument cluster when the system has detected a vehicle in the driving
path.
When the distance to a preceding
moving vehicle gets too small or when
approaching another vehicle too
rapidly and a collision is imminent, the
collision alert symbol pops-up in the
Driver Information Centre.
Simultaneously a warning chime
sounds. Depress the brake pedal, if it is required by the situation.
Deactivation
The system can be deactivated.
Press V repeatedly until the following
message appears in the Driver
Information Centre.
General information for both
variants of forward collision alert
9 Warning
Forward collision alert is just a
warning system and does not
apply the brakes. When
192Driving and operatingapproaching a vehicle ahead too
rapidly, it may not provide you
enough time to avoid a collision.
The driver accepts full
responsibility for the appropriate
following distance based on traffic, weather and visibility conditions.
The complete attention of the
driver is always required while
driving. The driver must always be
ready to take action and apply the
brakes.
System limitations
The system is designed to warn only for vehicles, but may react also onother metallic objects.
In the following cases, forward
collision alert may not detect a vehicle ahead or sensor performance is
limited:
● on winding roads
● when weather limits visibility, such as fog, rain, or snow
● when the sensor is blocked by snow, ice, slush, mud, dirt, or
windscreen damage
Following distance
indication
The following distance indication
displays the distance to a preceding
moving vehicle. The system uses,
depending on the vehicle equipment,
either the radar behind the radiator
grille or the front camera in the
windscreen to detect the distance of
a vehicle directly ahead in your path.
It is active at speeds above 40 km/h.
When a preceding vehicle is detected ahead, the distance is indicated inseconds, displayed on a page in the
Driver Information Centre 3 116.
Press MENU on the turn signal lever
to select Vehicle Information Menu
X and turn the adjuster wheel to
choose following distance indication
page.
The minimum indicated distance is 0.5 s.
If there is no vehicle ahead or the
vehicle ahead is out of range, two
dashes will be displayed: -.- s.
Active Emergency Braking Active emergency braking can help toreduce the damage from crashes with
vehicles and obstacles directly
ahead, when a collision can no longer be avoided either by manual braking
or by steering. Before the active
emergency braking applies, the driver is warned by the forward collision
alert 3 188.