174Driving and operating
vehicle speed increases or decreasesto 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.
25 km/h and brakes automatically to
follow a slower vehicle driving ahead
to a minimum speed of 15 km/h. On vehicles with automatic transmission
the system brakes to a stop.
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
since switching on ignition. Activation
in first gear is not possible.
Adaptive cruise control is mainly
advised to be used on long straight
roads like 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 3 106, m 3 106,
C 3 106.9 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 button C to switch on adaptive
cruise control. The control indicator
m or C in the instrument cluster
illuminates white.
Activation by setting the speed Adaptive cruise control can be
activated between 25 km/h and
180 km/h.
Accelerate to the desired speed and
turn thumb wheel to SET/-, the
current speed is stored and
178Driving and operating
Deactivation
Adaptive cruise control is deactivated by the driver when:
■ button 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 accelerates above 190 km/h or slows down below15 km/h (on vehicles with automatic transmission it slows down to a stop
without deactivating within
two minutes),
■ Traction Control system is operating for more than
20 seconds,
■ Electronic Stability Control is operating,■ there is no traffic and nothingdetected on the road sides for
several minutes. In this case there
are no radar echoes and the sensor
may report that it is blocked,
■ collision imminent braking is applying the brakes,
■ radar sensor is blocked by an ice or
water film,
■ fault is detected in the radar, engine
or brake system.
Additionally the system is
automatically deactivated on vehicles with automatic transmission (full
speed range adaptive cruise control)
when:
■ Electric parking brake is applied,
■ vehicle is being held to a stop by the
system for more than two minutes,
■ vehicle stops and a door is opened.
When adaptive cruise control is
deactivated automatically, the control indicator m or C illuminates white
and a warning symbol is displayed as a pop-up in the Driver Information
Centre.
The stored speed is maintained.
9 Warning
When adaptive cruise control is
deactivated, the driver must take
over full brake and engine control.
Switching off
Press button C to switch off adaptive
cruise control. The control indicator
m or C extinguishes. The stored
speed is deleted.
Switching off the ignition also
switches off adaptive cruise control
and deletes the stored speed.
Driving and operating179
Driver's attention■ Use adaptive cruise control carefully on bends or mountainroads, as it can lose the vehicle
ahead and need 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 of the vehicle.
■ 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 suppresses completelythe 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 pedestrians, animals or
stopped vehicles.
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
entering 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 on
the driving path or not. Adaptive
cruise control may not be able to
180Driving and operating
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 press 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.
Radar unit
The radar unit is mounted behind the
radiator grille below the brand
emblem.
9 Warning
The radar unit was aligned
carefully during manufacture.
Therefore, after a frontal accident, do not use the system. The front
bumper may appear to be intact,
however the sensor behind can be
out of position and react
incorrectly. After an accident,
Driving and operating181consult a workshop to verify and
correct the adaptive cruise control sensor position.
Settings
Settings can be changed in the
vehicle personalisation menu in the
Colour-Info-Display.
Select the relevant setting in Settings,
I Vehicle in the Colour-Info-Display.
Colour-Info-Display 3 114.
Vehicle personalisation 3 118.
Fault If the adaptive cruise control does not
work due to temporary conditions
(e.g. blockage by ice) or if there is a
permanent system error, then a
message is displayed in the Driver
Information Centre.
Vehicle messages 3 116.
Forward collision alert
The forward collision alert can help to
avoid or reduce the harm caused by
front-end crashes. If a vehicle directly
ahead is approached too quickly, a
warning chime and alert in the Driver
Information Centre is provided.
The green illuminated vehicle ahead
symbol A appears in the instrument
cluster when the system has detected
a vehicle in the driving path. A
precondition is that forward collision
alert is activated in the vehicle
personalisation menu 3 118 or that it
is not deactivated by the button V
(depending on the system, see
below).
Depending on the vehicle's
equipment, there are two variants of
the forward collision alert available:
■ Forward collision alert based on
radar system
on vehicles equipped with adaptive cruise control 3 173.
■ Forward collision alert based on
front camera system
on vehicles with no cruise control or
traditional cruise control only
3 171.
182Driving and operating
Forward collision alert based onradar systemThe system uses the radar sensor
behind the radiator grille to detect a
vehicle directly ahead, in your path,
within a distance of max. 150 metres.
Activation
Forward collision alert operates
automatically above walking speed,
provided that Auto Collision
Preparation setting is not deactivated
in the vehicle personalisation menu
3 118.
Selecting the alert sensitivity
The alert sensitivity can be set to
near, medium or far.
Press button E, the current setting is
shown in the Driver Information
Centre. Press button E again to
change the alert sensitivity. The
setting is also displayed in the Driver Information Centre.Note that the alert timing sensitivity
setting is shared with the following
distance setting of the adaptive cruise
control 3 173. So changing the alert
timing sensitivity changes the
adaptive cruise control following
distance setting.
Alerting the driver
184Driving and operating
Deactivation
The system can be deactivated.
Press button V repeatedly
until Forward Collision Alert Off
appears in the Driver Information
Centre.
General information for both
variants of forward collision alert9 Warning
Forward collision alert is just a
warning system and does not
apply the brakes. When
approaching 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 to
other metallic objects.
In the following cases, forward
collision alert may not detect a vehicle ahead or sensor performance may be limited:
■ on winding roads,
■ when weather limits visibility, e.g. 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 in
seconds, displayed on a page in the
Driver Information Centre 3 107.
On Baselevel display set Settings
X with the Menu button and
select Following distance indication
via the adjuster wheel on the turn signal lever 3 107.
On Midlevel or Uplevel display, select
Info menu and press o to
select Following distance indication
3 107.
The minimum indicated distance is
0.5 seconds.
Driving and operating185
If there is no vehicle ahead or the
vehicle ahead is out of range, two
dashes will be displayed: -.- s.
If Adaptive cruise control is active,
this page shows the following
distance setting instead 3 173.
Active Emergency Braking Active emergency braking can help to reduce 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 3 181.
The feature uses various inputs (e.g.
radar sensor, brake pressure, vehicle speed) to calculate the probability of
a frontal collision.
Active emergency braking operates automatically above walking speed, provided that Auto Collision
Preparation setting is not deactivated
in the vehicle personalisation menu
3 118.The system includes:
■ Brake preparation system
■ Emergency automatic braking
■ Forward looking brake assist9 Warning
This system is not intended to
replace the driver responsibility for driving the vehicle and looking
ahead. Its function is limited to
supplemental use only. The driver must continue to apply the brake
pedal as the driving situation
dictates.
Brake preparation system
When approaching a vehicle ahead
so quickly that a collision is likely, the brake preparation system slightly
pressurises the brakes. This reduces
the response time, when a manual or automatic braking is requested.
The brake system is prepared so that braking can occur more rapidly.
Emergency automatic braking
After the brake preparation and just
before the imminent collision, this
function automatically applies limited
braking to reduce the impact speed of
the collision.
Forward looking brake assist
In addition to the brake preparation
system and emergency automatic
braking, the forward looking brake
assist function makes the brake assist more sensitive. Therefore,
depressing the brake pedal slightly
results in immediate hard braking.
This function helps the driver brake
quicker and harder before the
imminent collision.9 Warning
Active emergency braking is not
designed to apply hard
autonomous braking or to
automatically avoid a collision. It is designed to reduce the vehicle
speed before a collision. It may not
react for stopped vehicles,