
Towing a trailer
If you couple up a trailer, make sure that you
have correctly established the electrical con-
nection. This can be accomplished by checking
the trailer lighting. Active Blind Spot Assist is
then deactivated. The indicator lamps in the
exterior mirrors light up yellow and the Active
Active
Blind Spot Assist not available when Blind Spot Assist not available when
towing a trailer See Owner's Manual towing a trailer See Owner's Manual
message appears in the multifunction display.
Active Lane Keeping Assist General notes
Active Lane Keeping Assist monitors the area in
front of your vehicle by means of multifunction
camera :at the top of the windscreen. Various
different areas to the front, rear and side of your vehicle are also monitored with the aid of the
radar sensor system. Active Lane Keeping
Assist detects lane markings on the road and
can warn you before you leave your lane unin-
tentionally. If you do not react to the warning, a
lane-correcting application of the brakes can
bring the vehicle back into the original lane.
This function is available within a speed range
between 60 km/h and 200 km/h.
For Active Lane Keeping Assist to assist you
when driving, the radar sensor system must be
operational.
Important safety notes If you fail to adapt your driving style, Active Lane Keeping Assist can neither reduce the risk of an
accident nor override the laws of physics. Active Lane Keeping Assist cannot take into account
road, weather or traffic conditions. Active Lane
Keeping Assist is only an aid. You are responsi-
ble for the distance to the vehicle in front, for
vehicle speed, for braking in good time and for
staying in lane. Active Lane Keeping Assist cannot continuously
keep your vehicle in its lane. G
WARNING
Active Lane Keeping Assist cannot always
clearly detect lane markings.
In such cases, Active Lane Keeping Assist
can:
R give an unnecessary warning and then
make a course-correcting brake application
to the vehicle
R neither give a warning nor intervene
There is a risk of an accident.
Always pay particular attention to the traffic
situation and keep within the lane, especially
if Active Lane Keeping Assist alerts you. Ter-
minate the intervention in a non-critical driv-
ing situation.
The system may be impaired or may not function if:
R there is poor visibility, e.g. due to insufficient
illumination of the road, or due to snow, rain,fog or spray
R there is glare, e.g. from oncoming traffic, the
sun or reflection from other vehicles (e.g. if
the road surface is wet)
R the windscreen is dirty, misted up, damaged
or covered, for instance by a sticker, in the
vicinity of the camera
R no or several, unclear lane markings are pres-
ent for one lane, e.g. in a construction area
R the lane markings are worn away, dark or cov-
ered up, e.g. by dirt or snow
R the distance to the vehicle in front is too small
and the lane markings thus cannot be detec-
ted
R the lane markings change quickly, e.g. lanes
branch off, cross one another or merge
R the road is narrow and winding
R there are highly variable shade conditions on
the roadway
R no vehicle is detected in the adjacent lane and
there are broken lane markings
Warning vibration through the steering
wheel A warning may be given if a front wheel passes
over a lane marking. It will warn you by means of 224
Driving systemsDriving an
d parking 

intermittent vibration in the steering wheel for
up to 1.5 seconds.
In order that you are warned only when neces-
sary and in good time if you cross the lane mark-
ing, the system detects certain conditions and
warns you accordingly.
The warning vibration occurs earlier if:
R you approach the outer lane marking on a
bend
R the road has very wide lanes, e.g. a motorway
R the system detects solid lane markings
The warning vibration occurs later if:
R the road has narrow lanes
R you cut the corner on a bend
Lane-correcting brake application G
WARNING
A lane-correcting brake application cannot
always bring the vehicle back into the original lane. There is a risk of an accident.
Always steer, brake or accelerate yourself,
especially if Active Lane Keeping Assist warns
you or makes a lane-correcting brake appli-
cation. G
WARNING
Active Lane Keeping Assist does not detect
traffic conditions or road users. In very rare
cases, the system may make an inappropriate brake application, e.g. after intentionally driv-
ing over a solid lane marking. There is a risk of an accident.
An inappropriate brake application may be
interrupted at any time if you steer slightly in
the opposite direction. Always make sure that
there is sufficient distance to the side for
other traffic or obstacles. If you leave your lane under certain circumstan-
ces, the vehicle will brake briefly on one side.
This is intended to help you return the vehicle to
the original lane.
If a lane-correcting brake application occurs,
display :appears in the multifunction display.
A lane-correcting brake application can be made
after driving over a lane marking recognised as
being solid or broken. Before this, a warning
must have been issued by means of intermittent
vibration through the steering wheel. In addi-
tion, a lane with lane markings on both sides
must be detected.
In the case of a broken lane marking being
detected, a lane-correcting brake application
can only be made if a vehicle has been detected
in the adjacent lane. The following vehicles can have an influence on brake application: oncom- ing traffic, vehicles that are overtaking and vehi-
cles that are driving parallel to your vehicle.
i A further lane-correcting brake application
can only occur after your vehicle has returned
to the original lane.
No lane-correcting brake application occurs if: R you clearly and actively steer, brake or accel-
erate
R you cut the corner on a sharp bend
R you have switched on the turn signal
R a driving safety system intervenes, such as
ESP ®
, PRE-SAFE ®
Brake or Active Blind Spot
Assist
R you have adopted a sporty driving style with
high cornering speeds or high rates of accel-
eration
R ESP ®
is deactivated
R the transmission is not in position D
R on vehicles with a trailer tow hitch, the elec-
trical connection to the trailer has been cor-
rectly established Driving systems
225Driving and parking Z 

R
an obstacle has been detected in the lane in
which you are driving
R a loss of tyre pressure or a defective tyre has
been detected and displayed
There is a possibility that the Active Lane Keep-
ing Assist could misjudge the given traffic sit-
uation. An inappropriate brake application may
be interrupted at any time if:
R you steer slightly in the opposite direction
R you switch on the turn signal
R you clearly brake or accelerate
A lane-correcting brake application is interrup-
ted automatically if:
R a driving safety system intervenes, such as
ESP ®
, PRE-SAFE ®
Brake or Active Blind Spot
Assist
R lane markings are no longer detected
Activating Active Lane Keeping Assist
X Activate Active Lane Keeping Assist using the
on-board computer; to do so, select Stand‐
Stand‐
ard ard orAdaptive
Adaptive (Ypage 245).
If you drive at speeds above 60 km/h and lane
markings are detected, the lines in the assis- tance graphic display (Y page 243) are
shown in green. Active Lane Keeping Assist is
ready for use.
If Standard
Standard is selected, no warning vibration
occurs if:
R you have switched on the turn signals. In
this event, the warnings are suppressed for a certain period of time.
R a driving safety system intervenes, such as
ABS, BAS or ESP ®
.
When Adaptive
Adaptive is selected, no warning vibra-
tion occurs if:
R you have switched on the turn signals. In
this event, the warnings are suppressed for
a certain period of time.
R a driving safety system intervenes, such as
ABS, BAS or ESP ®
.
R you accelerate hard, e.g. kickdown.
R you brake hard.
R you steer actively, e.g. swerve to avoid an
obstacle or change lane quickly.
R you cut the corner on a sharp bend. Towing a trailer
If you couple up a trailer, make sure that you
have correctly established the electrical con-
nection. This can be accomplished by checking
the trailer lighting. Lane-correcting brake appli-
cation does not take place when towing a trailer. Active Lane Keeping Assist is not activated and
the lines in the assistance graphic are grey. Towing a trailer
Important safety notes
G
WARNING
Vehicles with level control:
The vehicle level may be changed uninten-
tionally, e.g. by other persons. If this happens while you are coupling or decoupling a trailer,
you could become trapped. In addition, other
people could become trapped if their limbs
are between the vehicle body and the wheels or underneath the vehicle. There is a risk of
injury.
When coupling or decoupling a trailer, make
sure that no one:
R opens or closes the doors or the tailgate
R initiates a level change or turns the
DYNAMIC SELECT Controller
R locks or unlocks the vehicle G
WARNING
You could lose control of the vehicle/trailer
combination if it begins to swerve. The vehi-
cle/trailer combination could even overturn.
There is a risk of an accident.
On no account should you attempt to
straighten out the vehicle/trailer combina-
tion by increasing speed. Decrease your
speed and do not countersteer. Brake if nec-
essary. G
WARNING
If the maximum permissible load for a carrier system is exceeded, the carrier could come
loose from the vehicle and endanger other 226
Towing a trailerDriving and parking 

road users. There is a risk of an accident and
injury.
Never exceed the maximum permissible load
when using a carrier.
Exceeding the maximum permissible nose-
weight of the trailer drawbar on the ball coupling may cause damage to the following:
R your vehicle
R the trailer
R the ball coupling
R trailer tow hitch
The vehicle/trailer combination could become
unstable.
If the noseweight used is lower than the mini-
mum permissible noseweight, the vehicle/
trailer combination could also become unstable. To avoid hazardous situations:
R make sure to check the noseweight before
each journey
R use a drawbar noseweight as close as possi-
ble to the maximum noseweight
R do not exceed the maximum permissible
noseweight
R do not use a noseweight lower than the min-
imum noseweight
When reversing the vehicle towards the trailer,
make sure there is nobody between the trailer
and the vehicle.
Couple and uncouple the trailer carefully. If you
do not couple the trailer to the towing vehicle
correctly, the trailer could become detached.
Make sure that the following values are not
exceeded:
R the permissible trailer drawbar noseweight
R the permissible trailer load
R the permissible rear axle load of the towing
vehicle
R the maximum permissible gross vehicle
weight of both the towing vehicle and the
trailer
The applicable permissible values, which must
not be exceeded, can be found:
R in your vehicle documents
R on the identification plates of the trailer tow
hitch and the trailer
R on the vehicle identification plate
If the values differ, the lowest value applies. You will find the values approved by the manu-
facturer on the vehicle identification plates and those for the towing vehicle under "Technical
data" (Y page 385).
When towing a trailer, your vehicle's handling
characteristics will be different in comparison to
when driving without a trailer.
The vehicle/trailer combination:
R is heavier
R is restricted in its acceleration and gradient-
climbing capability
R has an increased braking distance
R is affected more by strong crosswinds
R demands more sensitive steering
R has a larger turning circle
This can impair the vehicle's handling charac-
teristics. Adapt your driving style accordingly.
Maintain a safe distance. Drive carefully.
When towing a trailer, always adjust your speed to the current road and weather conditions. Do
not exceed the maximum permissible speed for
your vehicle/trailer combination. Notes on towing a trailer
General notes Check the tyre pressures when towing a trailer.
You will find the values in the tyre pressure table in the vehicle fuel filler flap (Y page 351).
Please note that when towing a trailer, the fol-
lowing driving systems have limited availability
or are not available at all.
R PARKTRONIC (Y page 199)
R Blind Spot Assist (Y page 218)
R Active Lane Keeping Assist (Y page 224)
R Active Parking Assist (Y page 202)
On vehicles without level control, the height of
the ball coupling will alter according to the load
placed on the vehicle. If necessary, use a trailer
with a height-adjustable drawbar.
You will find fitting dimensions and loads under "Technical data" (Y page 384).
Driving tips Observe the information on ESP
®
trailer stabili-
sation (Y page 71) and on pulling away with a
trailer (Y page 149). Towing a trailer
227Driving and parking Z 

Until the ball coupling securely engages and
locks in a vertical position:
R indicator lamp ;flashes
R the multifunction display shows the display
message Trailer coupling extend‐
Trailer coupling extend‐
ing... ing....
The ball coupling swivels back into the out-of-
use position when:
R
R you drive off before the Trailer Trailercoupling coupling
extending...
extending... display message has disap-
peared from the multifunction display
R the ball coupling encounters an obstacle in
the swinging range Swinging out using the switch in the tail-
gate:
X Make sure that the vehicle is stationary.
X Open the tailgate.
X Pull switch :briefly.
After a short time the ball coupling swings out from under the rear bumper. It can take up to
seven seconds before the ball coupling visibly
swings out.
X Remove the protective covering from the ball
coupling and store it in a safe place.
Until the ball coupling securely engages and
locks in a vertical position:
R indicator lamp ;flashes
R the multifunction display shows the display
message Trailer coupling extend‐ Trailer coupling extend‐
ing...
ing....
The ball coupling swivels back into the out-of-
use position when:
R you drive off before the Trailer Trailercoupling
coupling
extending...
extending... display message has disap-
peared from the multifunction display
R the ball coupling encounters an obstacle in
the swinging range Further information:
R Display messages when towing a trailer
(Y page 281)
R Problems when swivelling the ball coupling
(Y page 233) Coupling up a trailer
Important safety notes G
WARNING
Vehicles with level control:
If you disconnect the trailer cable, the vehicle is lowered. This can cause you or others to
become trapped between the vehicle body
and tyres, or underneath the vehicle. This
poses a risk of injury.
Make sure that no-one is in the immediate
vicinity of the wheel arch or underneath the
vehicle when disconnecting the trailer cable.
Steel-sprung vehicles X
Shift the transmission to position P.
X Apply the electric parking brake.
X Position the trailer horizontally behind the
vehicle.
X Couple up the trailer.
X Establish the electrical connection between
the vehicle and the trailer.
X Check that the trailer lighting system is work-
ing.
X Push the combination switch upwards and
downwards and check whether the corre-
sponding turn signal on the trailer is flashing.
A connected trailer is only detected when the
electrical connection is established correctly
and when the lighting system is working prop-
erly. The function of other systems also depends on this, for example:
R ESP ®
R PARKTRONIC
R Active Parking Assist
R Active Blind Spot Assist
R Active Lane Keeping Assist Towing a trailer
229Driving and parking Z 

Vehicles with the AIRMATIC package
!
Before beginning the journey, make sure
that the trailer support wheel is completely
raised. Otherwise, the trailer or the vehicle
could be damaged by the lowered trailer sup- port wheel during the journey.
X Shift the transmission to position P.
X Apply the electric parking brake.
X Start the engine.
X Select the Comfortdrive program using the
DYNAMIC SELECT controller (Y page 195).
X Switch off the engine.
X Close the doors and tailgate.
X Position the trailer horizontally behind the
vehicle.
X Couple up the trailer.
X Establish the electrical connection between
the vehicle and the trailer.
X Check that the trailer lighting system is work-
ing.
X Push the combination switch upwards and
downwards and check whether the corre-
sponding turn signal on the trailer is flashing.
A connected trailer is only detected when the
electrical connection is established correctly
and when the lighting system is working prop-
erly. The function of other systems also depends on this, for example:
R ESP ®
R PARKTRONIC
R Active Parking Assist
R Active Blind Spot Assist
R Active Lane Keeping Assist
i Vehicles with the AIRMATIC package:
if
you couple up a trailer, the vehicle initially
remains at the selected level of the drive pro- gram set. Observe the following when cou-
pling up a trailer:
R If the normal level was not selected previ-
ously, the vehicle automatically adopts the
normal level starting from a speed of
30 km/h. Even at higher speeds, it does not drop below the normal level.
R Vehicle levels below the normal level are
not available.
R The raised level is available up to a speed of
30 km/h. R
This also applies when using accessories
that are plugged into the socket of the
trailer tow hitch (e.g. a bicycle rack).
R Before driving with a trailer, please observe
the information on the trailer support
wheel. Uncoupling a trailer
Important safety notes G
WARNING
If you uncouple a trailer with an engaged over- run brake, you could trap your hand between
the vehicle and the trailer drawbar. This poses a risk of injury.
Do not uncouple a trailer with an engaged
overrun brake. G
WARNING
Vehicles with level control:
If you disconnect the trailer cable, the vehicle is lowered. This can cause you or others to
become trapped between the vehicle body
and tyres, or underneath the vehicle. This
poses a risk of injury.
Make sure that no-one is in the immediate
vicinity of the wheel arch or underneath the
vehicle when disconnecting the trailer cable.
! Do not disconnect a trailer with an engaged
overrun brake. Otherwise, your vehicle could
be damaged by the rebounding of the overrun
brake.
! Remove the adapter cable before folding in
the ball coupling. You could otherwise dam-
age the rear bumper and the adapter cable.
Steel-sprung vehicles X
Shift the transmission to position P.
X Apply the electric parking brake.
X Secure the trailer against rolling away.
X Remove the trailer cable and decouple the
trailer. 230
Towing a trailerDriving an
d parking 

Selecting an entry from the telephone
book
X
Press the =or; button on the steering
wheel to select the Tel
Tel menu.
X Press the 9,:ora button to
switch to the phone book.
X Authorise access to the phone book on the
phone.
X Press the 9or: button to select the
desired name.
or
X To start rapid scrolling: press and hold9
or : for longer than one second.
Rapid scrolling stops when you release the
button or reach the end of the list.
X If only one telephone number is stored for
a name: press the 6ora button to
start dialling.
or
X If there is more than one number for a
particular name:
press the6ora
button to display the numbers.
X Press the 9or: button to select the
number you want to dial.
X Press the 6ora button to start dial-
ling.
or
X To exit the telephone book: press the~
or % button.
Redialling The on-board computer saves the last names or
numbers dialled in the redial memory.
X Press the =or; button on the steering
wheel to select the Tel
Tel menu.
X Press the 6button to switch to the redial
memory.
X Press the 9or: button to select the
desired name or number.
X Press the 6ora button to start dial-
ling.
or X To exit the redial memory: press the~
or % button. Assistance menu
Introduction Depending on the equipment fitted in the vehi-
cle, you have the following options in the
Assist. Assist. menu:
R Showing the assistance graphic
(Y page 243)
R Activating/deactivating the Traffic Sign
Assist display (Y page 244)
R Activating/deactivating Steering Assist and
Stop&Go Pilot (Y page 244)
R Activating/deactivating PRE-SAFE ®
Brake
(Y page 244)
R Activating/deactivating COLLISION PREVEN-
TION ASSIST PLUS (Y page 244)
R Activating/deactivating ATTENTION ASSIST
(Y page 244)
R Activating/deactivating Blind Spot Assist or
Active Blind Spot Assist (Y page 245)
R Activating/deactivating Lane Keeping Assist
or Active Lane Keeping Assist (Y page 245)
Showing the assistance graphic X
Press the =or; button on the steering
wheel to select the Assist. Assist.menu.
X Press 9or: to select Assistance Assistance
graphic
graphic.
X Confirm by pressing aon the steering
wheel.
The multifunction display shows the
DISTRONIC PLUS distance display in the
assistance graphic. Menus and submenus
243On-board computer and displays Z 

The assistance graphic shows you the status
of and/or information from the following driv-
ing systems or driving safety systems:
R Traffic Sign Assist (Y page 216)
R DISTRONIC PLUS (Y page 182)
R PRE-SAFE ®
Brake (Y page 72)
R COLLISION PREVENTION ASSIST PLUS
(Y page 67)
R ATTENTION ASSIST (Y page 214)
R Lane Keeping Assist (Y page 220) or Active
Lane Keeping Assist (Y page 224)
R DSR (Y page 193)
X Press :to display the ATTENTION ASSIST
assessment.
Traffic Sign Assist In the
Traffic Sign Assist
Traffic Sign Assist menu, you can
switch the Traffic Sign Assist message function
on or off. When the message function is activa-
ted, detected traffic signs and information
appear in the multifunction display for five sec-
onds.
X Press the =or; button on the steering
wheel to select the Assist. Assist.menu.
X Press the 9or: button to select
Traffic Sign Assist
Traffic Sign Assist.
X Confirm by pressing aon the steering
wheel.
The current selection appears.
X To activate/deactivate the message func-
tion: press aagain.
Further information about Traffic Sign Assist
(Y page 216).
Activating/deactivating Steering
Assist and Stop&Go Pilot X
Press the =or; button on the steering
wheel to select the Assist.
Assist. menu.
X Press the 9or: button to select DTR DTR
+: steer. asst.
+: steer. asst.
X Confirm by pressing aon the steering
wheel.
The current selection appears.
X To activate/deactivate: press theabut-
ton again.
When Steering Assist and Stop&Go Pilot are
activated, the multifunction display shows the DTR+: steering assistant
DTR+: steering assistant On Onmessage. Further information about DISTRONIC PLUS
with Steering Assist and Stop&Go Pilot
(Y page 190).
Activating/deactivating PRE-SAFE ®
Brake PRE‑SAFE
®
Brake is only available for vehicles
with the Driving Assistance package.
X Press the =or; button on the steering
wheel to select the Assist.
Assist.menu.
X Press the 9or: button to select PRE-
PRE-
SAFE brake
SAFE brake.
X Press ato confirm.
The current selection appears.
X To activate/deactivate: press theabut-
ton again.
When PRE-SAFE ®
Brake is deactivated, the
assistance graphic shows the æsymbol in
the multifunction display.
For more information on PRE ‑SAFE®
Brake, see
(Y page 72).
Activating/deactivating COLLISION
PREVENTION ASSIST PLUS X
Press the =or; button on the steering
wheel to select the Assist. Assist.menu.
X Press the 9or: button to select Col‐
Col‐
lision Prevent. Assist lision Prevent. Assist.
X Press ato confirm.
The current selection appears.
X To activate/deactivate: press theabut-
ton again.
When COLLISION PREVENTION ASSIST PLUS
is deactivated, the æsymbol appears in
the multifunction display in the assistance
graphic display.
Further information about COLLISION PREVEN- TION ASSIST PLUS (Y page 67).
Activating/deactivating ATTENTION
ASSIST X
Press the =or; button on the steering
wheel to select the Assist. Assist.menu.
X Press the 9or: button to select
Attention Assist
Attention Assist.
X Press the abutton.
The current selection appears.
X Press ato confirm. 244
Menus and submenusOn-board computer and displays