Driving and operating185It 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 will
not 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. If following a vehicle ahead
driving slower than 25 km/h, the
slower speed will be set. On vehicles
with automatic transmission, the
system can also brake to a stop.
Adaptive cruise control uses a radar
sensor to detect 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 or clutch pedal has been
depressed once after switching on
ignition.
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 3 110, m 3 110,
C 3 110.9 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 in the
instrument cluster illuminates white.
Additionally C appears in the Driver
Information Centre.
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
maintained. Control indicator m in the
instrument cluster illuminates green.
186Driving and operating
The adaptive cruise control symbol
C , the following distance setting and
set speed are indicated in the Driver
Information Centre. C illuminates
green.
The accelerator pedal can be
released. Adaptive cruise control
remains activated while gearshifting.
Overriding set speedIt 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 repeatedly operate
RES/+: speed increases in small
increments.
If the vehicle is driven with adaptive cruise control active 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
large increments, or repeatedly
operate SET/-: speed decreases in
small increments.
If the vehicle is driven with adaptive
cruise control active much slower
than the desired speed, e.g. because
of a slower vehicle ahead, then the
current speed can be stored and
maintained by turning the thumb
wheel to SET/-.
Resume stored speed
If the system is switched on but
inactive, then turn thumb wheel to
RES/+ at a speed above 25 km/h to
resume the stored speed.
Driving and operating187Full speed range adaptive cruise
control on vehicles with automatic transmission
Full speed range adaptive cruisecontrol will maintain a following gap
behind a detected vehicle and can
slow your vehicle to a stop behind that
vehicle.
When the vehicle ahead drives away
within two minutes, turn thumb wheel to RES/+ or operate the acceleratorpedal to reach a speed of 10 km/h to
resume full speed range adaptive cruise control.
If the stopped vehicle ahead begins to move forward and full speed range
adaptive cruise control has not
resumed, the green illuminated
vehicle ahead control indicator A will
flash and a warning chime will sound
as a reminder that the vehicle ahead
is pulling away.
When the vehicle ahead stops for
more than two minutes, the electric
parking brake will apply automatically and the full speed range adaptive
cruise control is deactivated. In this
event, drive the vehicle normally byoperating the accelerator pedal. Turn
thumb wheel to RES/+ at a speed
above 10 km/h to resume full speed
range adaptive cruise control.9 Warning
When full speed range adaptive
cruise control is deactivated or
cancelled, the vehicle will no
longer be held at a stop and can
start to move. Always be prepared
to manually apply the brake pedal
to hold the vehicle stationary.
Do not leave the vehicle while it is being held at a stop by the full
speed range adaptive cruise
control. Always move selector
lever to park position P and switch
off the ignition before leaving the
vehicle.
Setting the following distance
When adaptive cruise control detects a slower moving vehicle in the driving
path, it will adjust the vehicle speed to maintain the following distance
selected by the driver.
The following distance can be set to
near, medium or far.
Press E, the current setting is shown
in the Driver Information Centre.
Press E again to change the
following distance. The setting is also displayed in the Driver Information
Centre.
188Driving and operating
The selected following distance is
indicated by filled distance bars in the
adaptive cruise control page.
Note that the following distance
setting is shared with the sensitivity
setting of forward collision alert
3 192.
Example: If setting 3 (far) is selected,
then the driver is warned sooner
before a possible collision, also if
adaptive cruise control is inactive or
switched off.
9 Warning
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 when
the system detects a vehicle in the driving path.
Forward collision alert 3 192.
If this symbol does not display, or displays only 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 accelerates above
190 km/h or slows down below
15 km/h (on vehicles with
automatic transmission it slows
down to a stop without
deactivating within two minutes).
● The Traction Control system is operating.
● The Electronic Stability Control is
operating.
● There is no traffic and nothing detected on the road sides for
several minutes. In this case
there are no radar echoes and
the sensor may report that it is blocked.
Driving and operating189● The collision imminent brakingsystem is applying the brakes.
● The radar sensor is blocked by an ice or water film.
● A 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:
● The electric parking brake is applied.
● The vehicle is being held to a stop
by the system for more than
two minutes.
● The vehicle stops, the driver's seat belt is released and the
driver's door is opened.
When adaptive cruise control is
deactivated, the control indicator m
and C in the Driver Information
Centre changes from green to white
and a pop-up message is displayed.
The stored speed is maintained. The
system is deactivated but not
switched off.9 Warning
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 or C
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 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 completely 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.
Driving and operating191Hill and trailer considerations
System performance on hills 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 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.
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, in the event of a front-
end impact, 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, consult a workshop to
verify and correct the adaptive
cruise control sensor position.
Settings
Settings can be changed in thevehicle personalisation menu in the
Colour-Info-Display.
Select the relevant setting in Settings,
I Vehicle in the Colour-Info-Display.
Colour-Info-Display 3 118.
Vehicle personalisation 3 121.
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.
192Driving and operating
Vehicle messages 3 120.
Forward collision alert The forward collision alert can help to
avoid or reduce the harm caused by
front-end impacts.
A vehicle ahead is indicated by a
control indicator A.
If a vehicle directly ahead is
approached too quickly, a warning
chime and alert in the Driver
Information Centre is provided.
A precondition is that forward collision
alert is activated in the vehicle
personalisation menu 3 121 or that it
is not deactivated by pressing 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 3 184.
● Forward collision alert based on
front camera system
on vehicles with no cruise control or traditional cruise control only
3 181.
Forward collision alert based on
radar system
The 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
3 121.
Selecting the alert sensitivity
The alert sensitivity can be set to
near, medium or far.
Driving and operating193
Press E, the current setting is shown
in the Driver Information Centre.
Press 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 3 184. So changing the alert
timing sensitivity changes the
adaptive cruise control following
distance setting.
Alerting the driver
The vehicle ahead control indicator A illuminates green in the instrument
cluster when the system has detected
a vehicle in the driving path.
The control indicator A changes to
yellow when the distance to a
preceding moving vehicle gets too
short or when approaching another
vehicle too rapidly.Caution
The colour lighting of this control
indicator does not correspond to
local traffic laws on following
distance. The driver bears full
responsibility for maintaining safe
following distance according to
applicable traffic rules, weather
and road conditions etc. at all
times.
If a collision is imminent, the collision
alert symbol pops-up in the Driver
Information Centre and a warning
chime sounds. Depress the brake
pedal if it is required by the situation.