
The driving safety systems described only
work as effectively as possible when there is
adequate contact between the tires and the
road surface. Pay particular attention to the
information regarding tires, recommended
minimum tire tread depths etc. in the "Wheelsand tires" section ( Ypage 240).
In wintry driving conditions, always use winter tires (M+S tires) and if necessary, snow
chains. Only in this way will the driving safety
systems described in this section work as
effectively as possible.
ABS (Anti-lock Braking System)
General information
ABS regulates brake pressure in such a way
that the wheels do not lock when you brake.
This allows you to continue steering the vehi-
cle when braking. The ! ABS warning lamp in the instrument
cluster lights up when the ignition is switched on. It goes out when the engine is running.
Important safety notes
iObserve the "Important safety notes" sec-
tion ( Ypage 65).
GWARNING
If ABS is faulty, the wheels could lock when
braking. The steerability and braking charac-
teristics may be severely impaired. Addition-
ally, further driving safety systems are deac-
tivated. There is an increased danger of skid-
ding and accidents.
Drive on carefully. Have ABS checked imme-
diately at a qualified specialist workshop.
When ABS is malfunctioning, other systems,
including driving safety systems, will also
become inoperative. Observe the information on the ABS warning lamp ( Ypage 179) and
display messages which may be shown in the
instrument cluster ( Ypage 166).
ABS works from a speed of about 5 mph
(8 km/ h), regardless of road-surface condi- tions. ABS works on slippery surfaces, even
when you only brake gently.
Braking
X
If ABS intervenes: continue to depress the
brake pedal vigorously until the braking sit- uation is over.
X To make a full brake application:
depress the brake pedal with full force.
If ABS intervenes when braking, you will feel a pulsing in the brake pedal.
The pulsating brake pedal can be an indica-
tion of hazardous road conditions, and func-
tions as a reminder to take extra care while
driving.
BAS (Brake Assist System)
General information
BAS operates in emergency braking situa-
tions. If you depress the brake pedal quickly,
BAS automatically boosts the braking force,
thus shortening the stopping distance.
Important safety notes
iObserve the "Important safety notes" sec-
tion ( Ypage 65).
GWARNING
If BAS is malfunctioning, the braking distance
in an emergency braking situation is
increased. There is a risk of an accident.
In an emergency braking situation, depress
the brake pedal with full force. ABS prevents
the wheels from locking.
Braking
X
Keep the brake pedal firmly depressed until
the emergency braking situation is over.
ABS prevents the wheels from locking.
The brakes will function as usual once you
release the brake pedal. BAS is deactivated.
66Driving safety systems
Safety

The brakes will work normally again if:
R you release the brake pedal.
R there is no longer any danger of a collision.
R no obstacle is detected in front of your vehicle.
Adaptive Brake Assist is then deactivated.
If adaptive Brake Assist demands particularly
high braking force, preventative passenger
protection measures (PRE-SAFE ®
) are activa-
ted simultaneously.
Up to a speed of approximately 155 mph
(250 km/ h), adaptive Brake Assist is capable
of reacting to moving objects that have
already been detected as such at least once
over the period of observation.
Up to a speed of approximately 44 mph
(70 km/h), adaptive Brake Assist reacts to
stationary obstacles.
ESP®(Electronic Stability Program)
General notes
iObserve the "Important safety notes" sec-
tion ( Ypage 65).
ESP ®
monitors driving stability and traction,
i.e. power transmission between the tires and
the road surface.
If ESP ®
detects that the vehicle is deviating
from the direction desired by the driver, one
or more wheels are braked to stabilize the
vehicle. The engine output is also modified to keep the vehicle on the desired course within
physical limits. ESP ®
assists the driver when
pulling away on wet or slippery roads. ESP ®
can also stabilize the vehicle during braking.
ETS/4ETS (Electronic Traction System)
iObserve the "Important safety notes" sec-
tion ( Ypage 65).
ETS traction control is part of ESP ®
. On vehi-
cles with 4MATIC, 4ETS is part of ESP ®
.
Traction control brakes the drive wheels indi-
vidually if they spin. This enables you to pull away and accelerate on slippery surfaces, for
example if the road surface is slippery on one side. In addition, more drive torque is trans-
ferred to the wheel or wheels with traction.
Traction control remains active, even if you
deactivate ESP ®
.
Important safety notes
GWARNING
If ESP ®
is malfunctioning, ESP ®
is unable to
stabilize the vehicle. Additionally, further driv- ing safety systems are deactivated. This
increases the risk of skidding and an accident.
Drive on carefully. Have ESP ®
checked at a
qualified specialist workshop.
Vehicles without 4MATIC: observe the notes
on ESP ®
(Y page 234) when towing the vehi-
cle with a raised rear axle.
ESP ®
is only deactivated if the åwarning
lamp is lit continuously.
If the ÷ warning lamp lights up continu-
ously, ESP ®
is not available due to a malfunc-
tion.
Observe the information on warning lamps ( Y page 181) and display messages which
may be shown in the instrument cluster( Y page 166).
Only use wheels with the recommended tire
sizes. Only then will ESP ®
function properly.
Characteristics of ESP®
General information
If the ÷ ESP warning lamp goes out before
beginning the journey, ESP ®
is automatically
active.
If ESP ®
intervenes, the ÷ESP®
warning
lamp flashes in the instrument cluster.
Driving safety systems71
Safety
Z

Useful information
iThis Operator's Manual describes all
models and all standard and optional equip- ment of your vehicle available at the time of
publication of the Operator's Manual.
Country-specific differences are possible.
Please note that your vehicle may not be
equipped with all features described. This
also applies to safety-related systems and
functions.
iRead the information on qualified special-
ist workshops ( Ypage 27).
SmartKey
Important safety notes
GWARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shifting the automatic transmission out of
park position P
R Start the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children.
GWARNING
If you attach heavy or large objects to the
SmartKey, the SmartKey could be uninten-
tionally turned in the ignition lock. This could
cause the engine to be switched off. There is a risk of an accident.
Do not attach any heavy or large objects to the SmartKey. Remove any bulky key rings before
inserting the SmartKey into the ignition lock.
!Keep the SmartKey away from strong
magnetic fields. Otherwise, the remote
control function could be affected.
Strong magnetic fields can occur in the
vicinity of powerful electrical installations.
Do not keep the SmartKey: R with electronic devices, e.g. a mobile
phone or another SmartKey
R with metallic objects, e.g. coins or metalfoil
R inside metallic objects, e.g. a metal case
This can affect the functionality of the
SmartKey.
Vehicles with KEYLESS-GO start function: do not keep the SmartKey on the parcel shelf or in the trunk. Otherwise, the SmartKey maynot be detected, e.g. when starting the engine
using the Start/Stop button.
A check which periodically establishes a radio
connection between the vehicle and the
SmartKey determines whether a valid Smart- Key is in the vehicle. This occurs, for example:
R when starting the engine
R whilst driving
R when using HANDS-FREE ACCESS
R when the external door handles are
touched
R during convenience closing
78SmartKey
Opening and closing

SmartKey functions
:&To lock the vehicle
;FTo open/close the trunk lid
=%To unlock the vehicle
X To unlock centrally: press button=.
If you do not open the vehicle within
approximately 40 seconds of unlocking:
R the vehicle is locked again.
R the anti-theft alarm system is armedagain.
X To lock centrally: press button:.
The SmartKey centrally locks/unlocks:
R the doors
R the trunk lid
R the fuel filler flap
The turn signals flash once when unlocking
and three times when locking.
iYou can also set an audible signal to con-
firm that the vehicle has been locked. The
audible signal can be activated and deacti-
vated using COMAND (see the Digital Oper- ating Instructions).
iWhen the surround lighting is activated in
COMAND, it comes on when it is dark after
the vehicle is unlocked using the remote
control. Information on activating and
deactivating the surround lighting can be
found in the Digital Operator's Manual.
X To open the trunk lid automatically
from outside the vehicle: press and hold
button ;until the trunk lid opens.
KEYLESS-GO
General notes
Bear in mind that the engine can be started by any of the vehicle occupants if there is a
SmartKey in the vehicle.
Locking/unlocking centrally
You can start, lock or unlock the vehicle using KEYLESS-GO. To do this, you only need carry
the SmartKey with you. You can combine the
functions of KEYLESS-GO with those of a con- ventional SmartKey. Unlock the vehicle by
using KEYLESS-GO, for instance, and lock it
using the &button on the SmartKey.
The driver's door and the door at which the
handle is used, must both be closed. The
SmartKey must be outside the vehicle. When
locking or unlocking with KEYLESS-GO, the
distance between the SmartKey and the cor-
responding door handle must not be greater
than 3 ft (1 m).
A check which periodically establishes a radio
connection between the vehicle and the
SmartKey determines whether a valid Smart- Key is in the vehicle. This occurs, for example:
R when starting the engine
R whilst driving
R when using HANDS-FREE ACCESS
R when the external door handles aretouched
R during convenience closing
SmartKey79
Opening and closing
Z

XTo unlock the vehicle: touch the inner
surface of the door handle.
X To lock the vehicle: touch sensor sur-
face :or; .
Make sure that you do not touch the inner
surface of the door handle.
X Convenience closing feature: touch
recessed sensor surface ;for an exten-
ded period.
Deactivating
If you do not intend to use the vehicle for a
longer period of time, you can deactivate KEY-
LESS-GO. The SmartKey will then use very lit-
tle power, thereby conserving battery power.
For the purposes of activation/deactivation,
the vehicle must not be nearby. X To deactivate: press the&button on
the SmartKey twice in rapid succession.
The battery check lamp of the SmartKey
lights up twice briefly and KEYLESS-GO is
deactivated.
X To activate: press any button on the
SmartKey or insert the SmartKey into the
ignition lock.
KEYLESS-GO and all of its associated fea-
tures are available again.
KEYLESS-GO start function
Bear in mind that the engine can be started by any of the vehicle occupants if there is a
SmartKey in the vehicle.
Changing the settings of the locking
system
You can find information about this in the
Digital Operator's Manual.
Mechanical key
General notes
If the vehicle can no longer be locked or
unlocked with the SmartKey or KEYLESS-GO, use the mechanical key.
If you use the mechanical key to unlock and
open the driver's door, the anti-theft alarm
system will be triggered. Switch off the alarm
( Y page 76).
If you unlock the vehicle using the mechanical key, the fuel filler flap will not be unlocked
automatically.
X To unlock the fuel filler flap: insert the
SmartKey into the ignition lock.
Removing the mechanical key
X Push release catch :in the direction of
the arrow and at the same time remove
mechanical key ;from the SmartKey.
For further information about: R unlocking the driver's door ( Ypage 83)
R unlocking the trunk ( Ypage 88)
R locking the vehicle ( Ypage 83)
Inserting the mechanical key
X
Push mechanical key ;completely into
the SmartKey until it engages and release catch :is back in its basic position.
80SmartKey
Opening and closing

opens. Do not hold battery compartment cover:closed while doing so.
X Remove battery compartment cover :.
X
Repeatedly tap the SmartKey against your
palm until battery =falls out.
X Insert the new battery with the positive ter-
minal facing upwards. Use a lint-free cloth
to do so.
X Make sure that the surface of the battery is
free of lint, grease and other contaminants.
X Insert the front tabs of battery compart-
ment cover :into the housing first and
then press to close it.
X Insert mechanical key ;into the Smart-
Key.
X Check the function of all SmartKey buttons
on the vehicle.
Problems with the SmartKey
You can find information about this in the
Digital Operator's Manual.
Doors
Important safety notes
GWARNING
If children are left unsupervised in the vehicle, they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shifting the automatic transmission out of
park position P
R Start the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children.
You should preferably place luggage or loads in the trunk. Observe the loading guidelines( Y page 196).
Information in the Digital Operator's
Manual
In the Digital Operator's Manual you will find
information on the following topics: R
Unlocking and opening doors from the inside
R Centrally locking and unlocking the vehicle
from the inside
R Automatic locking feature
R Power closing
82Doors
Opening and closing

Useful information
iThis Operator's Manual describes all
models and all standard and optional equip- ment of your vehicle available at the time of
publication of the Operator's Manual.
Country-specific differences are possible.
Please note that your vehicle may not be
equipped with all features described. This
also applies to safety-related systems and
functions.
iRead the information on qualified special-
ist workshops ( Ypage 27).
Correct driver's seat position
GWARNING
You could lose control of your vehicle if you do
the following while driving:
R adjust the driver's seat, head restraint,
steering wheel or mirrors
R fasten the seat belt
There is a risk of an accident.
Adjust the driver's seat, head restraint, steer-
ing wheel and mirror and fasten your seat belt before starting the engine.
X Observe the safety guidelines on seat
adjustment ( Ypage 97).
X Check whether you have adjusted seat =
properly ( Ypage 98).
When adjusting the seat, make sure that:
R you are as far away from the driver's air bag
as possible
R you are sitting in a normal upright position
R you can fasten the seat belt properly
R you have moved the backrest to an almost
vertical position
R you have set the seat cushion angle so that
your thighs are gently supported
R you can depress the pedals properly
X Check whether the head restraint is adjus-
ted properly.
When doing so, make sure that you have
adjusted the head restraint so that the back of your head is supported at eye level by the center of the head restraint.
X Observe the safety guidelines on steering
wheel adjustment ( Ypage 99).
X Make sure that steering wheel :is adjus-
ted properly ( Ypage 99).
When adjusting the steering wheel, make
sure that:
R you can hold the steering wheel with your
arms slightly bent
R you can move your legs freely
R you can see all the displays in the instru-
ment cluster clearly
X Observe the safety guidelines for seat belts
( Y page 44).
X Check whether you have fastened seatbelt ;properly ( Ypage 46).
The seat belt should:
R fit snugly across your body
R be routed across the middle of your shoul-der
R be routed in your pelvic area across the hip
joints
96Correct driver's seat position
Seats, steering wheel and mirrors

the case if you are not depressing the brake
pedal.
If you depress the brake pedal and press the
Start/Stop button, the engine starts immedi-
ately.
A check which periodically establishes a radio
connection between the vehicle and the
SmartKey determines whether a valid Smart- Key is in the vehicle. This occurs, for example, when starting the engine.
To start the vehicle without actively using the
SmartKey:
R the Start/Stop button must be inserted in
the ignition lock.
R the SmartKey must be in the vehicle.
R the vehicle must not be locked with the
SmartKey or KEYLESS-GO ( Ypage 79).
Do not keep the SmartKey:
R with electronic devices, e.g. a mobile
phone or another SmartKey
R with metallic objects, e.g. coins or metal
foil
R inside metallic objects, e.g. a metal case
This can affect the functionality of the Smart- Key.
If you lock the vehicle with the SmartKey's
remote control or with KEYLESS-GO, after a
short time:
R you will not be able to switch on the ignition
with the Start/Stop button.
R you will not be able to start the engine with
the Start/Stop button until the vehicle is
unlocked again.
If you lock the vehicle centrally using the but-
ton on the front door ( Ypage 82), you can
continue to start the engine with the Start/
Stop button.
The engine can be turned off while the vehicle
is in motion by pressing and holding the
Start/Stop button for approximately three
seconds. This function operates independ-
ently of the ECO start/stop automatic engine switch-off function. SmartKey positions with the Start/Stop
button
:Start/Stop button
;Ignition lock
As soon as the ignition is switched on, all the
indicator lamps in the instrument cluster light up. If an indicator lamp does not go out afterstarting the engine or lights up while driving,
see ( Ypage 178).
If Start/Stop button :has not yet been
pressed, this corresponds to the SmartKey
being removed from the ignition.
X To switch on the power supply: press
Start/Stop button :once.
The power supply is switched on. You can
now activate the windshield wipers, for
example.
The power supply is switched off again if:
R the driver's door is opened and
R you press Start/Stop button :twice when
in this position
X To switch on the ignition: press Start/
Stop button :twice.
The ignition is switched on.
The ignition is switched off when:
R the driver's door is opened and
R you press Start/Stop button :once when
in this position
116Driving
Driving an d parking