156Driving and operatingStop-start systemThe stop-start system helps to save
fuel and to reduce the exhaust
emissions. When conditions allow, it
switches off the engine as soon as the
vehicle is at a low speed or at a
standstill, e.g. at a traffic light or in a
traffic jam. It starts the engine
automatically as soon as the clutch is depressed. A vehicle battery sensor
ensures that an Autostop is only
performed if the vehicle battery is
sufficiently charged for a restart.
Activation The stop-start system is available as
soon as the engine is started, the
vehicle starts-off and the conditions
as stated below in this section are
fulfilled.Deactivation
Deactivate the stop-start system
manually by pressing the eco button.
Deactivation is indicated by the LED in the button extinguishing.
Autostop If the vehicle is at a low speed or at a
standstill, activate an Autostop as
follows:
■ Depress the clutch pedal
■ set the lever to neutral
■ release the clutch pedal
The engine will be switched off while the ignition stays on.
An Autostop is indicated by the
needle at the AUTOSTOP position in
the tachometer.
During an Autostop, the heating and
brake performance will be
maintained.
Caution
The steering assist can be
reduced during an Autostop.
Conditions for an Autostop
The stop-start system checks if each
of the following conditions is fulfilled.
Driving and operating167Caution
It is not advisable to drive with thehand resting on the selector lever.
Brakes
The brake system comprises two independent brake circuits.
If a brake circuit fails, the vehicle can
still be braked using the other brake
circuit. However, braking effect is
achieved only when the brake pedal
is depressed firmly. Considerably
more force is needed for this. The
braking distance is extended. Seek the assistance of a workshop before
continuing your journey.
When the engine is not running, the
support of the brake servo unit
disappears once the brake pedal has been depressed once or twice.
Braking effect is not reduced, but
braking requires significantly greater
force. It is especially important to bear
this in mind when being towed.
Control indicator R 3 109.
Antilock brake system
Antilock brake system (ABS)
prevents the wheels from locking.ABS starts to regulate brake pressure as soon as a wheel shows a tendency to lock. The vehicle remains
steerable, even during hard braking.
ABS control is made apparent
through a pulse in the brake pedal
and the noise of the regulation
process.
For optimum braking, keep the brake
pedal fully depressed throughout the
braking process, despite the fact that
the pedal is pulsating. Do not reduce
the pressure on the pedal.
After starting off the system performs
a self-test which may be audible.
Control indicator u 3 110.
Adaptive brake light During full braking, all three brake
lights flash for the duration of ABS
control.
168Driving and operating
Fault9Warning
If there is a fault in the ABS, the
wheels may be liable to lock due
to braking that is heavier than
normal. The advantages of ABS are no longer available. During
hard braking, the vehicle can no longer be steered and may
swerve.
Have the cause of the fault remedied
by a workshop.
Parking brake
Manual parking brake
Always apply parking brake firmly
without operating the release button,
and apply as firmly as possible on a
downhill or uphill slope.
To release the parking brake, pull the lever up slightly, press the release
button and fully lower the lever.
To reduce the operating forces of the
parking brake, depress the foot brake
at the same time.
Control indicator R 3 109.
Electric parking brake
Applying when vehicle is stationary
Pull switch m for approx.
one second; the electric parking
brake is applied automatically with an adequate force. For maximum force,
e.g. parking with trailer or on inclines:
pull switch m twice.
The electric parking brake is applied
when control indicator m illuminates
3 109.
The electric parking brake can always
be activated, even if the ignition is off.
176Driving and operating
The limited speed will flash in the
Driver Information Centre and a
chime sounds during this period.
Release the accelerator pedal and the speed limiter function is
reactivated once a speed lower than
the limit speed is obtained.
Deactivation
Press button y: speed limiter is
deactivated and the vehicle can be
driven without speed limit.
The limited speed is stored and a
corresponding message appears in
the Driver Information Centre.
Resume limit speed
Turn thumb wheel to RES/+. The
stored speed limit will be obtained.
Switching off
Press button L, the speed limit
indication in the Driver Information
Centre extinguishes. The stored
speed is deleted.By pressing button m to activate
cruise control or adaptive cruise
control or by switching off the ignition,
speed limiter is also deactivated and
the stored speed is deleted.
Adaptive cruise control
Adaptive cruise control is an
enhancement to traditional cruise
control with the additional feature of maintaining a certain distance behind the vehicle ahead.
Adaptive cruise control automatically
decelerates the vehicle when
approaching a slower moving vehicle. It 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 willnot exceed the set speed. It may
apply limited braking with activated
brake lights.
The adaptive cruise control can store
and maintain speeds over approx.
30 mph and brakes automatically tofollow a slower vehicle driving ahead
down to a minimum speed of
18 mph.
Adaptive cruise control uses a radar
sensor to detect the 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 has been depressed once after
switching on ignition. Activation in first gear is not possible.
Adaptive cruise control is mainly
advised to be used on long straight
roads, e.g. 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 3 113, m 3 113.
Driving and operating181
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 stopped vehicles,
pedestrians or animals.
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
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 in
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 depress the brake
pedal, if you need to brake more
quickly.
184Driving and operating
Press button E; the current setting is
shown in the Driver Information
Centre. Press button 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 lights up 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.
Driving and operating185
SettingsSettings can be changed in the Auto
collision preparation menu in the
vehicle personalisation 3 127.
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 button V, see below.
Selecting the alert sensitivity
The alert sensitivity can be set to
near, medium or far.
Press button V; the current setting is
shown in the Driver Information
Centre. Press button V again to
change the alert sensitivity.
Alerting the driver
A green illuminated vehicle ahead
control indicator A lights up 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.
Driving and operating187
The minimum indicated distance is
0.5 s.
If there is no vehicle ahead or the vehicle ahead is out of range, two
dashes will be displayed: -.- s.
Active Emergency Braking
Active emergency braking can help to reduce the damage 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 3 183.
The feature uses various inputs (e.g.
radar sensor, brake pressure, vehicle speed) to calculate the probability of
a frontal collision.
Active emergency braking operates automatically above walking speed,
provided that Auto collision
preparation setting is not deactivated
in the vehicle personalisation menu
3 127.
The system includes: ■ Brake preparation system
■ Emergency automatic braking
■ Forward looking brake assist9 Warning
This system is not intended to
replace the driver responsibility of driving the vehicle and looking
ahead. Its function is limited to
supplemental use only. The driver
shall continue to apply the brake
pedal as the driving situation
dictates.
Brake preparation system
When approaching a vehicle ahead
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.
The brake system is prepared so that braking can occur more rapidly.
Emergency automatic braking After the brake preparation and just
before the imminent collision, this
function automatically applies limited
braking to reduce the impact speed of
the collision.
Forward looking brake assist
In addition to brake preparation
system and emergency automatic
braking, the forward looking brake
assist function makes the brake assist more sensitive. In this way,
depressing the brake pedal slightly