166Driving and operatingBrakes
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 3 112.
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 3 113.
Adaptive brake light During full braking, all three brake
lights flash for the duration of ABS
control.
Fault9 Warning
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
9 Warning
Before leaving the vehicle, check
parking brake status. Control
indicator R (manual parking
brake) or m (electrical parking
brake) must illuminate constantly.
Driving and operating1799Warning
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 when
the system detects a vehicle in the driving path.
Forward collision alert 3 182.
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.
● 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
45 km/h.
● The Traction Control system is operating.
● Electronic Stability Control is operating.
● 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.
● The active emergency braking system is applying the brakes.● Driving on steep inclines.
● 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, 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 and
indicated in brackets in the Driver
Information Centre. 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.
180Driving and operatingSwitching 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 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 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 completely suppresses 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.
● Don't use adaptive cruise control when towing a trailer.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
182Driving and operatingRadar 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
vehicle personalisation menu in the
Info-Display.
Select the relevant setting in
Settings in the Info-Display.
Info-Display 3 121.
Vehicle personalisation 3 125.
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.
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 3 125 or that it
is not deactivated by pressing V
(depending on the system, see
following).
Driving and operating185Alerting 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.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 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 and a
warning chime sounds. Depress the
brake pedal, if it is required by the
situation.
Deactivation
The system can be deactivated.
Press V repeatedly until Forward
Collision Alert Off appears in the
Driver Information Centre.
General information for both
variants of forward collision alert9 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.
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
The system is designed to warn only for vehicles, but may react also onother metallic 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 system uses,
Driving and operating187Brake preparation system
When approaching a vehicle ahead
so quickly that a collision is likely, the brake preparation system slightlypressurises 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
results immediately in a strong
braking. This function helps the driver
brake quicker and stronger before the imminent collision.9 Warning
Active emergency braking is not
designed to apply strong
autonomous braking or to avoid automatically a collision. It is
designed to reduce the vehicle
speed before collision. It may not
react on stopped vehicles,
pedestrians or 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 shall 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.
System limitations
The active emergency braking has
limited or no function during rain,
snow or heavy dirt, as the radar
sensor can be covered by a water
film, dust, ice or snow. In case of
sensor blockage, clean the sensor
cover.
In some seldom cases the active
emergency braking system may
provide a short automatic braking in
situations that seem to be
unnecessary, for instance due to
traffic signs in a curve or due to
vehicles in another lane. This is
acceptable operation, the vehicle
does not need service. Firmly apply
the accelerator pedal to override the
automatic braking.
Settings
Settings can be changed in the
vehicle personalisation menu in the
Info-Display.
Select the relevant setting in
Settings in the Info-Display.
Vehicle personalisation 3 125.
Fault
In the event of a system service
requirement, a message is displayed
in the Driver Information Centre.
Driving and operating203Note
In the event of an accident, switch off
the ignition and lights.
Refuelling9 Danger
Before refuelling, switch off
ignition and any external heaters
with combustion chambers.
Switch off any mobile phones.
Follow the operating and safety
instructions of the filling station
when refuelling.
9 Danger
Fuel is flammable and explosive.
No smoking. No naked flames or
sparks.
If you can smell fuel in your
vehicle, have the cause of this
remedied immediately by a
workshop.
Caution
In case of misfuelling, do not
switch on ignition.
Fuel filler flap is located at right rear
side of the vehicle.
The fuel filler flap can only be opened
if the vehicle is unlocked. Release the
fuel filler flap by pushing the flap.
Petrol and Diesel refuelling To open, turn the cap slowly
anticlockwise.
204Driving and operating
The fuel filler cap can be retained in
the bracket on the fuel filler flap.
To refuel, fully insert the pump nozzle
and switch it on.
After the automatic cut-off, the tank can be topped up by operating the
pump nozzle a maximum of two more
times.
Caution
Wipe off any overflowing fuel
immediately.
To close, turn the fuel filler cap
clockwise until it clicks.
Close the flap and allow it to engage.
Vehicles with misfuel inhibitor9 Warning
Do not try to open the flap of the
fuel filler neck manually on
vehicles with misfuel inhibitor.
Disregarding this could lead to
trapping of the fingers.
Vehicles with a selective catalytic
reduction system are equipped with a
misfuel inhibitor.
The misfuel inhibitor ensures that the flap of the fuel filler neck can only be
opened by using a nozzle for diesel
fuel or a funnel for emergency
refilling.
Turn the fuel filler cap slowly
anticlockwise.
The cap can be retained in the
bracket on the fuel filler flap.
Place the nozzle in a straight line to the filler neck and press with slight
force to insert.
In case of an emergency, refill with a
canister. A funnel must be used to
open the cap of the filler neck.