Driving and operating163Drive systems
All-wheel drive The All-wheel drive system enhances
driving characteristics and stability,
and helps to achieve the best
possible driveability regardless of
ground surface. The system is always
active and cannot be deactivated.
The torque is distributed steplessly
between the wheels of the front and rear axle, depending on the driving
conditions. Additionally the torque
between the rear wheels is distributed depending on the surface.
For optimum system performance,
the vehicle's tyres should not have
varying degrees of wear.
If a service message is displayed in
the Driver Information Centre, the
system may have limited functionality
(or be completely disabled in some
cases, i.e. the vehicle switches to
Front-wheel drive). Seek the
assistance of a workshop.
Towing the vehicle 3 254.Brakes
The brake system comprises twoindependent 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 3 102.
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 3 103.
Adaptive brake light During full braking, all three brakelights flash for the duration of ABS
control.
168Driving and operating
Additionally the selected mode is
displayed as status message in the
Driver Information Centre.
If the vehicle comes into threshold
with deactivated ESP, the system will reactivate ESP for the time duration
of the threshold, when the brake pedal is depressed once.
ESC is reactivated by pressing the
b button again. If the TC system was
previously disabled, both TC and
ESC are reactivated.
ESC is also reactivated the next time
the ignition is switched on.Interactive driving system
Flex Ride Flex Ride driving system allows the
driver to select between three driving
modes:
■ SPORT mode: press button SPORT , LED illuminates.
■ TOUR mode: press button TOUR,
LED illuminates.
■ NORMAL mode: neither button SPORT nor TOUR is pressed, no
LED illuminates.
Deactivate SPORT mode and TOUR
mode by pressing corresponding
button once more.
In each driving mode Flex Ride networks the following electronic systems:
■ Continuous Damping Control.
■ Accelerator Pedal Control.
■ Steering Control.
■ All-wheel drive.
■ Electronic Stability Control (ESC).■ Antilock brake system (ABS) with cornering brake control (CBC).
■ Automatic transmission.
SPORT mode
The settings of the systems are
adapted to a sportier driving style:
■ Damping of shock absorbers reacts
more stiffly to provide better contact with the road surface.
■ The engine reacts more quickly to the accelerator pedal.
■ Steering support is reduced.
■ Engine torque of All-wheel drive is distributed more to the rear axle.
Driving and operating169
■ Shift points of automatictransmission occur later.
■ With SPORT mode activated, the illumination of main instruments
changes from white to red.
TOUR mode
The settings of the systems are
adapted to a comfort driving style:
■ Damping of shock absorbers reacts
more softly.
■ Accelerator pedal reacts with standard settings.
■ Steering support is in standard mode.
■ Engine torque of All-wheel drive isdistributed mainly to the front axle.
■ Shift points of automatic transmission occur in a comfort
mode.
■ Illumination of main instruments is white.
NORMAL mode
All settings of the systems are
adapted to standard values.
Drive mode control
Within each manually selected driving mode SPORT, TOUR or NORMAL,
the Drive Mode Control (DMC)
detects and analyses continuously
the real driving characteristic,
responses by the driver, and the
active dynamic state of the vehicle. If
necessary, the control unit of DMC
automatically changes the settings
within the selected driving mode or,
when recognising greater variations,
the driving mode is changed for the
length of variation.
If, for example, NORMAL mode is
selected and DMC detects a sporty
driving behaviour, DMC changesseveral settings of the Normal mode
into sporty settings. The DMC
changes to SPORT mode in case of
very sporty driving behaviour.
If, for another example, TOUR mode
is selected and whilst driving on a
winding road a sudden hard brake is
necessary, DMC will detect the
dynamic vehicle condition and
changes the settings for suspension
to SPORT mode to increase vehicle
stability.
When the driving characteristic or the
dynamic vehicle state returns to the
former state, DMC will change the
settings to the preselected driving
mode.
Personalised settings in SPORT
mode
The driver can select the functions of
the SPORT mode when SPORT
button is pressed.
Select the relevant settings in
Settings , I Sport Mode in the Colour-
Info-Display.
Colour-Info-Display 3 114.
Vehicle personalisation 3 118.
170Driving and operating
Flex Ride - OPC VersionThe OPC Version of Flex Ride systemworks in the same way as the
standard Flex Ride system with the
difference that the modes have a
more sporty characteristic.OPC Flex Ride driving system allows
the driver to select between three
driving modes:
■ OPC mode: press button OPC,
LED illuminates.
■ SPORT mode: press button SPORT , LED illuminates.
■ NORMAL mode: neither button SPORT nor OPC is pressed, no
LED illuminates.
Deactivate SPORT mode and OPC mode by pressing corresponding
button once more.
In each driving mode OPC Flex Ride
networks the following electronic systems:
■ Continuous Damping Control.
■ Accelerator Pedal Control.
■ Steering Control.
■ All-wheel drive.
■ Electronic Stability Control (ESC).
■ Antilock brake system (ABS) with cornering brake control (CBC).
■ Automatic transmission.OPC mode
The drive dynamic characteristics are adapted to high performance
settings.
In this mode the illumination of main
instruments is switched to red.
SPORT mode
The settings of the systems are
adapted to a sportier driving style.
NORMAL mode
In NORMAL mode, when neither
SPORT nor OPC button is pressed,
all settings of the systems are
adapted to standard values.
Personalised settings in the OPC
mode
The driver can select the functions of
the OPC mode when OPC button is
pressed.
Select the relevant settings in
Settings , I Sport Mode in the Colour-
Info-Display.
Colour-Info-Display 3 114.
Vehicle personalisation 3 118.
Driving and operating171Driver assistance
systems9 Warning
Driver assistance systems are
developed to support the driver
and not to replace his attention.
The driver accepts full
responsibility when driving the
vehicle.
When using driver assistance
systems, always take care
regarding the current traffic
situation.
Cruise control
The cruise control can store and
maintain speeds of approx. 30 to
200 km/h. Deviations from the stored
speeds may occur when driving uphill or downhill.
For safety reasons the cruise control cannot be activated until the foot
brake has been operated once.
Activating in first gear is not possible.
Do not use the cruise control if it is not advisable to maintain a constant
speed.
With automatic transmission, only
activate cruise control in automatic
mode.
Control indicator m 3 106.
Switching on Press button m, control indicator m in
instrument cluster illuminates white.
Activation
Accelerate to the desired speed and
turn thumb wheel to SET/-: the
current speed is stored and
maintained. Control indicator m in
instrument cluster illuminates green.
Set speed is indicated on midlevel or
uplevel display near m symbol.
Accelerator pedal can be released.
Vehicle speed can be increased by depressing the accelerator pedal.
When the accelerator pedal is
released, the previously stored speed
is resumed.
Cruise control remains activated
while gearshifting.
Driving and operating173
Press button L. The control indicator
L in the instrument cluster illuminates
white. If cruise control or adaptive
cruise control has been activated
before, it is switched off when speed
limiter is activated and the control
indicator m extinguishes.
Set speed limit
With speed limiter active, hold thumb
wheel turned to RES/+ or briefly turn
to RES/+ repeatedly until the desired
maximum speed is displayed in the
Driver Information Centre.
Alternatively accelerate to the desired speed and briefly turn thumb wheel to SET/- : the current speed is stored as
maximum speed. Speed limit is
displayed in the Driver Information
Centre.
Control indicator L in the instrument
cluster illuminates green.
Change speed limit
With speed limiter active, turn thumb
wheel to RES/+ to increase or SET/-
to decrease the desired maximum
speed.
Exceeding the speed limit
In the event of an emergency it is
possible to exceed the speed limit by
depressing the accelerator pedal
firmly beyond the point of resistance.
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
Driving and operating177
Press button E, the current setting is
shown in the Driver Information
Centre. Press button E again to
change the following distance. The
setting is also displayed in the Driver
Information Centre.The selected following distance is
indicated by filled distance bars in the
adaptive cruise control page.
Note that the following distance
setting is shared with the sensitivity
setting of forward collision alert
3 181.
Example: If setting 3 (far) is selected,
then the driver is warned sooner
before a possible collision, also if
adaptive cruise control is inactive or
switched off.
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
The green illuminated vehicle ahead
control indicator A is displayed when
the system detects a vehicle in the driving path.
If this symbol does not display, or
displays briefly, adaptive cruise
control will not respond to vehicles
ahead.
Driving and operating179
Driver's attention■ Use adaptive cruise control carefully on bends or mountainroads, 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 completelythe visibility. 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 or
stopped vehicles.
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 on
the driving path or not. Adaptive
cruise control may not be able to