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Driving and operating183start moving. Be always prepared
to manually apply the brake to hold the vehicle stationary.
Do not leave the vehicle while it is
being held at a stop by 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 tomaintain the following distance
selected by the driver.
The following distance can be set to
close (1 bar), normal (2 bars) or far
(3 bars).
If the engine is running and the
adaptive cruise control is enabled
(grey), you can modify the following
distance setting:
Press GAP, the current setting is
shown in the Driver Information
Centre.
Press GAP again to change the
following distance: The new setting is
displayed in the Driver Information
Centre.
The selected following distance is
indicated by full bars in the adaptive
cruise control page.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
If the system does not detect a vehicle
in the driving path, U is displayed
in the Driver Information Centre. The system operates as conventional
cruise control.
If the system detects a vehicle in the
driving path, V is displayed in the
Driver Information Centre. The
system operates as conventional
cruise control.
If the system detects a vehicle in the
driving path which is too close or too
slow, it adjusts the speed accordingly. X is displayed in the Driver
Information Centre.
If the system reaches the limit of
adjusting the speed and the driver
does not react to this situation, the
system is automatically deactivated
and W is displayed in the Driver
Information Centre.
If the set speed is temporarily
exceeded by the driver, the system is automatically deactivated and Z is
displayed in the Driver Information Centre.
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184Driving and operatingDeactivation of the functionality
Press button to deactivate the
functionality. The cruise control is in
pause mode and a message is
displayed. The vehicle is driven
without cruise control.
Cruise control is deactivated, but not
switched off. Last stored speed
remains in memory for later speed
resume.
Cruise control is deactivated
automatically:
● maximum deviation of20 mph between set speed and speed of
the vehicle ahead reached
● distance between vehicle and vehicle ahead too small
● vehicle speed below 25 mph
● speed of the vehicle ahead too slow
● Traction Control system or Electronic Stability Control
operating
● selected following distance reached
● another vehicle inserts between vehicle and vehicle ahead
● following distance cannot be maintained, e.g., in the case of a
steep descentSwitching off the system
Turn to 0 to switch off the system. The
symbol 5 and a message are
displayed in the Driver Information
Centre.
Switching off the ignition deletes the
stored set speed.
Driver's attention ● Use the adaptive cruise control carefully on bends or mountain
roads, as it can lose the vehicle
ahead and needs time to detect it again.
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Driving and operating185● Do not use the system onslippery roads as it can create
rapid changes in tyre traction
(wheel spinning), so that the
control of the vehicle can be lost.
● Do not use the system when the spare wheel is in use.
System limits9 Warning
The system's automatic brake
force does not permit hard braking and the braking level may not be
sufficient to avoid a collision.
● The control range is limited to a maximum deviation of 20 mph
between the set speed and the
speed of the vehicle ahead.
● 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.
● The adaptive cruise control does ignore the oncoming traffic.
● The adaptive cruise control does not consider pedestrians and
animals for braking and driving
off.
● The adaptive cruise control considers stopped vehicles onlyat low speed.
● Do not use the adaptive cruise control when towing a trailer.
● Do not use the adaptive cruise control on roads with an incline ofmore than 10%.
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 I 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
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186Driving and operatingthe 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 while 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 considerations9 Warning
Do not use the adaptive cruise
control on steep hill roads.
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.
Fault
In the event of a fault with the adaptive
cruise control, a warning light is
illuminated and a message is
displayed in the instrument cluster,
accompanied by a warning chime.
The adaptive cruise control may not
operate correctly if traffic signs do not comply with the Vienna Convention
on Road Signs and Signals.
Have the system checked by a dealer
or a qualified workshop.
As a safety measure, do not use the
system if the brake lights are faulty.
Forward collision alert
The forward collision alert may help to avoid or reduce the harm caused by
front-end crashes.
The forward collision alert uses the
front camera in the windscreen and a radar sensor in the front bumper to
detect a preceding vehicle directly
ahead, in your path.
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Driving and operating187If a vehicle directly ahead is
approached too quickly, a warning
chime and alert in the Driver
Information Centre is provided.9 Warning
Forward collision alert is just a
warning system and does not
apply the brakes. When
approaching a vehicle ahead too
rapidly, there may not be 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.
Activation
Forward collision alert detects
vehicles and operates automatically
at all speeds above 3 mph and
53 mph. The system detects
stationary vehicles if the speed does
not exceed 50 mph.
Alerting the driver
The driver is warned by following
alerts:
● Symbol I illuminates and a
warning message is displayed in the Driver Information Centre
when the distance to the vehicle
ahead gets to small.
● Symbol I illuminates, a
warning message is displayed in the Driver Information Centre and
a warning chime sounds, when a collision is imminent and
immediate driver's action is
required.9 Warning
Forward collision alert is just a
warning system and does not
apply the brakes. When
approaching a vehicle ahead too
rapidly, there may not be 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.
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
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188Driving and operatingapplicable traffic rules, weather
and road conditions etc. at all
times.
Selecting the alert sensitivity
The alert sensitivity has to be set to
close, normal or distant in the vehicle personalisation menu 3 123.
The chosen setting will remain until it
is changed. The alert timing will vary
based on vehicle speed. The faster
the vehicle speed, the farther away
the alert will occur. Consider traffic
and weather conditions when
selecting the alert timing.
Deactivation The system can only be deactivated
by deactivating the active emergency
braking in the vehicle personalisation
3 123.
System limitations
Forward collision alert is designed to
warn on vehicles only, but may react
also to other objects.
In the following cases, forward
collision alert may not detect a vehicle ahead or sensor performance is
limited:
● driving on winding or hilly roads
● driving during nighttime
● weather limits visibility, such as fog, rain, or snow
● the sensor in the windscreen is blocked by snow, ice, slush, mud,dirt etc.
● the windscreen is damaged or affected by foreign objects, e.g.
stickers
Active emergency braking
Active emergency braking can help to reduce the damage and injury from
crashes with vehicles, pedestrians
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 or the front pedestrian protection
alert.Forward collision alert 3 186
Front pedestrian protection 3 190
The feature uses various inputs (e.g.
camera sensor, radar sensor, brake
pressure, vehicle speed) to calculate
the probability of a frontal collision.9 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 to reduce
the vehicle speed before a
collision.
The system may not react to
animals. After a sudden lane
change, the system needs a
certain time to detect the next
preceding vehicle.
The driver must always be ready
to take action and apply the brakes and steer to avoid collisions.
Page 191 of 289

Driving and operating189FunctionalityActive emergency braking is
equipped with a front camera and
operates in forward gear above
walking speed up to 53 mph. The
system detects stationary vehicles
only if the speed does not exceed
50 mph. Pedestrians are detected
only if the speed does not exceed
37 mph.
A precondition is that active
emergency braking is not deactivated
in the vehicle personalisation menu
3 123.
If deactivated, m illuminates in the
instrument cluster and a warning
message is displayed in the Driver
Information Centre.
If the system has been deactivated, it
is reactivated automatically the next
time the ignition is switched on.
The system includes: ● emergency automatic braking
● forward collision alert
● front pedestrian protectionEmergency automatic braking
After activation of brake preparation
system and just before the imminent
collision, this function automatically
applies limited braking to reduce the
impact speed of the collision or
prohibit a crash.
If active emergency braking is
applied, m flashes in the instrument
cluster.
Depending on the situation, the
vehicle may automatically brake
moderately or hard.
Front automatic braking can only
occur if a vehicle or a pedestrian
ahead is detected.
Forward collision alert 3 186
Front pedestrian protection 3 190
Below a speed of 19 mph, emergency automatic braking may slow down thevehicle to a complete stop. If the
speed exceeds 19 mph, emergency
automatic braking reduces the speed.
However, the driver must apply the
brake.Emergency automatic braking may
slow the vehicle to a complete stop to try to avoid a potential crash. If the
vehicle comes to a complete stop,
automatic braking is maintained for
up to 2 seconds.
● Automatic transmission: If the vehicle comes to a complete
stop, keep the brake pedal
depressed to prevent the vehicle
from starting off again.
● Manual transmission: If the vehicle comes to a completestop, the engine may stall.
Operation of the function may be felt
by a slight vibration in the brake
pedal.9 Warning
Emergency automatic braking is
an emergency crash preparation
feature and is not designed to
avoid crashes. Do not rely on the
system to brake the vehicle.
Emergency automatic braking will
not brake outside of its operating
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190Driving and operatingspeed range and only responds to
detected vehicles and
pedestrians.
System limitations
In some cases, the active emergencybraking system may provide an
automatic braking in situations that
seem to be unnecessary, for instance
in parking garages, due to traffic signs
in a curve or due to vehicles in
another lane. This is normal
operation, the vehicle does not need
service. Firmly apply the accelerator
pedal to override the automatic
braking if the situation and the
surroundings permit.
In the following cases, active
emergency braking performance is
limited:
● Driving on winding or hilly roads.
● Detecting all vehicles, especially vehicles with a trailer, tractors,
muddy vehicles, etc.
● Detecting a vehicle when weather limits visibility, such as infog, rain, or snow.
● Driving during nighttime.
● The windscreen is damaged or affected by foreign items, e.g.
stickers.
Complete attention is always required
while driving, and the driver should be ready to take action and apply the
brakes and / or steer the vehicle to
avoid crashes.
We recommend to deactivate the
system in the vehicle personalisation
in the following cases:
● when towing a trailer or caravan
● when carrying long objects on roof bars or a roof rack
● when the vehicle is being towed with the engine running
● when tyre chains are fitted
● when a spare wheel is fitted that is smaller than the other wheels
● before using an automatic car wash with the engine running
● before placing the vehicle on a rolling road in a workshop
● if the windscreen has been damaged close to the camera● if the front bumper has beendamaged
● if the brake lamps are not working
Fault
In case the system requires a service, m is illuminated in the instrument
cluster, a message is displayed in the
Driver Information Centre and an
audible signal is given.
If the system does not work as it
should do, vehicle messages are
displayed in the Driver Information
Centre.
Vehicle messages 3 122.
Front pedestrian protection Front pedestrian protection may help
to avoid or reduce the harm caused
by front-end crashes with pedestrians when driving forward.
The system uses the front camera in
the windscreen and a radar sensor in
the front bumper to detect a
pedestrian directly ahead in your path.