Driving and operating185Detecting the vehicle ahead
The green illuminated vehicle ahead
control indicator A is displayed when
the system detects a vehicle in the driving path. The range of the sensors
is between 25 and 150 m depending
on vehicle speed.
Forward collision alert 3 189.
If this symbol does not display, or
displays briefly, adaptive cruise
control will not respond to vehicles
ahead.
Indication on Driver Assistance page
If the system is active and a preceding vehicle is detected, the bars in front of the vehicle symbol appear green and
indicate set gap position.
Deactivation of the functionality
Adaptive cruise control is deactivated by the driver when:
● y is pressed.
● Brake pedal is applied.
● Clutch pedal is depressed for more than 4 seconds.
● Selector lever of automatic transmission is moved to N.
The system is also automatically
deactivated when:
● Vehicle speed accelerates above
120 mph or slows down below
15 mph. Vehicles with automatic
transmission slows down to a
stop without deactivating within
5 minutes.
● The Traction Control system is deactivated or operating.
● The Electronic Stability Control is
deactivated or operating.
● There is no traffic and nothing detected on the road sides forapprox. 1 minute. In this case
there are no radar echoes and
the sensor may report that it is blocked.
● The active emergency braking system is applying the brakes.
● Driving on steep inclines.
● The radar sensor is blocked by an ice or water film.
● A fault is detected in the radar, camera, engine or brake system.
● The brakes need to cool down.
186Driving and operatingAdditionally, the system is
automatically deactivated on vehicles
with automatic transmission (full
speed range adaptive cruise control)
when:
● The incline uphill or downhill is greater than 20%.
● The electric parking brake is applied.
● The vehicle is being held to a stop
by the system for more than
5 minutes.
● The vehicle stops, the driver's seat belt is unbuckled and thedriver's door is opened.
When adaptive cruise control is
deactivated, the control indicator C
changes from green to white and a
pop-up message is displayed in the
Driver Information Centre.
The stored speed is maintained.The stored speed is indicated in
brackets in the Driver Information
Centre when the system is
deactivated but not switched off.
The adaptive cruise control symbol
C changes from green to white when
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
immediately.
Switching off the system
Press v to switch off adaptive cruise
control. The control indicator C
extinguishes in the Driver Information Centre. 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 needs 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.
188Driving and operatinga 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 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. Full speed range
adaptive control is deactivated
automatically, as the vehicle is
stopping uphill on an incline greater than 10%. In this condition, be
prepared to take control of the
vehicle.
Note that applying the brake
deactivates the system.
Radar unit
The radar unit is mounted behind the
radiator grille or 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
Driving and operating189accident, consult a workshop to
verify and adjust the radar unit
position.
Settings
A vehicle message and chime
reminds the driver to drive off when
the adaptive cruise control holds the vehicle at standstill. This function
named Go Notifier can be activated
and deactivated in the vehicle
personalisation menu in the Info
Display.
Vehicle personalisation 3 122.
Fault
If the adaptive cruise control does not work due to temporary conditions
(e.g. blockage by ice, overheated
brakes or low speed manoeuvres) or if there is a permanent system error,
a message is displayed in the Driver
Information Centre.
Vehicle messages 3 121.
Forward collision alert
The forward collision alert is part of
the forward collision system 3 122. It
can help to avoid or reduce the harm
caused by front-end crashes.
A vehicle ahead is indicated by the
control indicator A.
Additionally, the status of the forward
collision alert is indicated on the
Driver Assistance page in the Driver
Information Center 3 110.
If the vehicle is equipped with
conventional cruise control, the
forward collision alert uses the front
camera in the windscreen to detect a
vehicle directly ahead, in your path.
If the vehicle is equipped with
adaptive cruise control, the forward
collision alert uses the radar sensor
and front camera to detect a vehicle
directly ahead, in your path.
Forward collision alert with front
camera detects vehicles to distances
of approx. 60 m and operates
automatically at all speeds above
walking speed.Forward collision alert with radar
sensor detects vehicles to distances
of approx. 150 m and operates
automatically at all speeds above
walking speed.
Activation A precondition is that forward collision
alert in the vehicle personalisation
menu is not deactivated 3 122.
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. On
vehicles with head-up display, A is
projected on the windscreen.
The control indicator A changes to
amber when the distance to a
preceding moving vehicle gets too
small.Caution
The colour lighting of this control
indicator does not correspond to
local traffic laws on following
192Driving and operatingGeneral information9Warning
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
Forward collision alert is designed to warn on vehicles only, but may reactalso 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● during nighttime driving
● weather limits visibility, such as fog, rain, or snow
● the sensor in the windscreen is blocked by snow, ice, slush, mud,dirt, windscreen damage or
affected by foreign items, e.g.
stickers
Following distance
indication
The following distance indication
displays the distance to a preceding
moving vehicle. The front camera in
the windscreen and the Radar sensor
are used to detect the distance of a
vehicle directly ahead in the vehicle's
path. It is active at speeds above
25 mph.When a preceding vehicle is detected
ahead, the distance is indicated in
seconds, displayed on a page in the
Driver Information Centre.
On Baselevel display, choose Info
Menu ? and choose following
distance indication page 3 110.
On Mid- and Uplevel display, select
Info menu via steering wheel buttons
and press å to select following
distance indication 3 110.
The minimum indicated distance is 0.5 seconds.
If there is no vehicle ahead or the vehicle ahead is out of range, two
dashes will be displayed: -.- sec.
Driving and operating193
If Adaptive cruise control is active,
this page shows the alert sensitivity
setting instead of following distance setting 3 180.
System limitations
In the following cases, following
distance indication sensor
performance is limited:
● Driving on winding or hilly roads.
● During nighttime driving.
● Weather limits visibility, such as fog, rain, or snow.
● The sensor is blocked by snow, ice, slush, mud, dirt, windscreen
damage or affected by foreign
items, e.g. stickers.
Active emergency braking Active emergency braking is part of
the forward collision system 3 122. It
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 3 189 or the Front pedestrian
protection alert 3 196.
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's 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.
Functionality
The system includes: ● brake preparation system
● emergency automatic braking
● forward looking brake assist
● intelligent brake assist (only with radar sensor)
● front pedestrian protection system
194Driving and operatingIf equipped only with front camera the
active emergency braking operates in forward gear above walking speed up
to 50 mph.
If equipped with radar sensor, active
emergency braking operates in
forward gear at all speeds above
walking speed. Only front pedestrian
protection is active up to 50 mph.
Activation
A precondition is that Forward
Collision System and Front
pedestrian detection are not
deactivated in the vehicle
personalisation menu 3 122.
Brake preparation system
When approaching a vehicle ahead
or a pedestrian 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.Emergency 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, a message appears in the Driver Information Center and a
chime sounds.
Depending on the situation, the
vehicle may automatically brake
moderately or hard. This front
automatic braking can only occur if a
vehicle ahead is detected, indicated by the vehicle ahead indicator A
3 189. On vehicles with front
pedestrian protection, front automatic braking can also occur when a
pedestrian ahead is detected.
Below a speed of 25 mph the system
can apply full braking.
Emergency automatic braking may
slow the vehicle to a complete stop to
try to avoid a potential crash. If this
happens, emergency automatic
braking may engage the electricparking brake to hold the vehicle at a
stop. To release press the electric
parking brake button or firmly press
the accelerator 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 speed range and only responds to
detected vehicles and
pedestrians.
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, pressing
the brake pedal less strongly results
in immediate hard braking. This
function helps the driver brake
quicker and harder before the
imminent collision.
Driving and operating1959Warning
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 to animals. After a sudden
lane change, the system needs a
certain time to detect the next
preceding vehicle.
The complete attention of the
driver is always required while
driving. The driver must always be
ready to take action and apply the brakes and steer to avoid
collisions.
The system is designed to work with
all occupants wearing their seat belts.
Intelligent Brake Assist
If the vehicle is equipped with radar
sensor Intelligent brake assist may
activate when the brake pedal is
applied quickly by providing a boost
to braking based on the speed of
approach and distance to a vehicle
ahead.
Minor brake pedal pulsations or pedal movement during this time is normal
and the brake pedal should continue
to be applied as needed. Intelligent
brake assist will automatically
disengage only when the brake pedal is released.9 Warning
Intelligent brake assist may
increase vehicle braking in
situations when it may not be
necessary. You could block the
flow of traffic. If this occurs, take
your foot off the brake pedal and
then apply the brakes as needed.
Front pedestrian protection 3 196.
Deactivation Active emergency braking can be
deactivated in the personalisation
menu 3 122. If deactivated a
message is displayed in the Driver
Information Centre.
We recommend to deactivate the
system or set it to alert only in the
following cases:
● when the vehicle is being towed
● if a trailer is attached to the vehicle
● before using an automatic car wash with ignition switched on
● if the windscreen has been damaged close to the camera
● if the front bumper has been damaged
System limitations In some cases, the active emergency
braking 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.