186Driving and operatingIncrease speed
With adaptive cruise control active,
hold thumb wheel turned to RES/+:
speed increases continuously in large increments, or activate repeatedly
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 activate
repeatedly 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 thecurrent 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.
Full speed range adaptive cruise
control on vehicles with automatic
transmission
Full speed range adaptive cruise
control will maintain a following gap
behind a detected vehicle and slow
your vehicle to a stop behind that
vehicle.
In case of a brief stop of the vehicle
ahead the adaptive cruise control will
resume automatically without driver
action. If necessary on some
versions, press RES/+ or the
accelerator pedal to resume adaptive cruise control.
If the stopped vehicle ahead was
stopped for a longer time and then
begins to move forward, the green
illuminated vehicle ahead controlindicator A will flash and a warning
chime will sound as a reminder to
check traffic before proceeding.
When the vehicle ahead drives away,
press RES+ or the accelerator pedal
to resume adaptive cruise control. If
stopped for more than two minutes or
if the driver door is opened and the
driver safety belt is unbuckled, the
electric parking brake is applied
automatically to hold the vehicle. m
will turn on. To release electric parking brake press the accelerator pedal. Electric parking brake 3 1759 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 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
188Driving and operatingIf this symbol does not display, or
displays 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.
● 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 forseveral minutes. 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, 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 safety belt is unbuckled and the
driver's door is opened.When adaptive cruise control is
deactivated, the control indicator m
changes from green to white and a
pop-up message is displayed in the
Driver Information Centre.
The stored speed is maintained.
On Midlevel display the stored speed
is indicated in brackets in the Driver
Information Centre when system is
deactivated but not switched off.
On Uplevel display the adaptive
cruise control symbol C changes
from green to white when 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.
Driving and operating189Switching off
Press C to switch off adaptive cruise
control. The control indicator m and
C in the Driver Information Centre
extinguish. 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 thevisibility. 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,
very slow speed driving or
stopped vehicles.
● Do not use adaptive cruise control when towing a trailer.
● Do not use adaptive cruise control on steep inclines.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
190Driving and operatingentering 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
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
9 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. 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.
192Driving and operatingA precondition is that forward collision
alert with front camera system is not
deactivated by pressing V on the
steering wheel or, with radar sensor,
that it is not deactivated in the vehicle
personalisation menu 3 123.
Activation
Forward collision alert with front
camera detects vehicles to distances
of approximately 60 metres and
operates automatically at all speeds
above walking speed.
Forward collision alert with radar
sensor detects vehicles to distances
of approximately 150 metres and
operates automatically at all speeds
above walking speed.
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
small 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.
When the time to a potential collision
with a vehicle in front gets too small
and a collision is imminent, the
collision alert symbol pops-up in the
Driver Information Centre and the
driver gets notified by a flashing red
LED stripe which is projected on the
windscreen in the driver's field of
view.
Simultaneously a warning chime sounds. Depress the brake pedal and
steer the vehicle, if it is required by the
situation.
Selecting the alert sensitivity Press V or E to set the alert
sensitivity to near, medium or far and
on some versions off.
Driving and operating193
The first button press shows the
current setting on the Driver
Information Centre. Additional button
presses will change this setting. 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.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.
Deactivation
The system can be deactivated.
On forward collision alert with radar
sensor the system can be disabled by the personalisation menu, 3 123.
On forward collision alert with front
camera press V repeatedly until
Forward Collision Alert Off appears in
the Driver Information Centre.
If the forward collision alert was
deactivated, alert sensitivity is set to
"medium" when ignition is switched on next time.
The last selected setting will be stored
when the ignition is switched off.
General information9 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.
194Driving and operatingThe 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 react
also to other objects.
In the following cases, forward
collision alert may not detect a vehicle
ahead or sensor performance is
limited:
● on winding roads
● when weather limits visibility, such as fog, rain, or snow
● when the sensor 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 is used to detect the
distance of a vehicle directly ahead in
the vehicle's 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.
On Midlevel display, choose Info
Menu ? via MENU on the turn
signal lever and turn the adjuster
wheel to choose following distance
indication page, 3 114On Uplevel display, select Info menu
via steering wheel buttons and press o to select following distance
indication 3 114.
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.
If Adaptive cruise control is active,
this page shows the alert sensitivity
setting instead of following distance
setting. 3 184.
Driving and operating195Active emergency braking
Active emergency braking can help to reduce the damage and injury 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 3 191.
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 for
pedestrians or animals. After a
sudden lane change, the system
needs a certain time to detect the
next preceding vehicle.
The driver shall always be ready to take action and apply the brakes
and steer to avoid collisions.
Functionality
If equipped only with front camera the active emergency braking operates in
forward gear above walking speed up to 85 km/h.
With radar sensor active emergency
braking operates in forward gear
above walking speed at all speeds.
A precondition is that forward collision
alert with front camera system is not
deactivated by pressing V on the
steering wheel 3 191or, with radar
sensor, that it is not deactivated in the
vehicle personalisation menu 3 123.
The system includes: ● brake preparation system
● emergency automatic braking
● forward looking brake assist
● intelligent brake assist (only with radar sensor)
Brake preparation system
When approaching a vehicle ahead
so quickly that a collision is likely, the brake preparation system slightlypressurizes 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.
If equipped only with front camera the system operates up to a speed of 80
km/h.
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. Depending on the
situation, the vehicle may
automatically brake moderately or
hard. This front automatic braking can