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180Driving and operating9Warning
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.
Activation by setting the speed
Adaptive cruise control can be
activated between 30 mph and
112 mph.
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.
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Driving and operating181
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
large increments, or activate SET/-
repeatedly: speed decreases in small
increments.
With adaptive cruise control active, if
the vehicle is driven 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 30 mph to
resume the stored speed.
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
on the Driver Information Centre.
Press E again to change the
following distance. The setting is also displayed in the top line of the Driver
Information Centre.
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182Driving and operating
The selected following distance is
indicated by filled distance bars on
the adaptive cruise control page.
Note that the following distance
setting is shared with the sensitivity
setting of forward collision alert.
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 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 28 mph or accelerates above
120 mph.
■ Traction Control system is operating for more than
20 seconds.
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Driving and operating183
■ Electronic Stability Control isoperating.
■ 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.
■ 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.
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 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 mountainroads, 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.
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Driving and operating185
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,
consult a workshop to verify and
correct the adaptive cruise control
sensor position.
Settings
Settings can be changed in the Auto
collision preparation menu in the
vehicle personalisation 3 129.
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.
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186Driving and operating
Vehicle messages 3 123.
Forward collision alert The forward collision alert can help to
avoid or reduce the damage caused
by front-end crashes.
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 3 129 or that it
is not deactivated by pressing V
(depending on the system, see
following).
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 3 179.
■ Forward collision alert based on
front camera system
on vehicles with traditional cruise
control or none 3 176.
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
3 129.
Selecting the alert sensitivity
The alert sensitivity can be set to
near, medium or far.
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Driving and operating187
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 top line of the Driver
Information Centre.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.
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188Driving and operating
SettingsSettings 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 25 mph, 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.
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.