2012 MERCEDES-BENZ A-CLASS HATCHBACK Owners Manual

Blind Spot Assist is only an aid. It may fail to
detect some vehicles and is no substitute for
attentive driving.
General notes
Blind Spot Assist uses a radar sensor system to monitor the areas on both sides of your
vehicle. It supports you from speeds of
30 km/h. A warning display in the exterior
mirrors draws your attention to vehicles
detected in the monitored area. If you then
switch on the corresponding turn signal to
change lane, you will also receive an optical
and audible collision warning. For this pur-
pose, Blind Spot Assist uses sensors in the
rear bumper.
The radar sensor system is switched off auto-
matically in the vicinity of radio telescope
facilities (Y page 350).
For Blind Spot Assist to assist you when driv-
ing, the radar sensor system must be:
R activated(Y page 223)
R operational
i In some countries you must deactivate
the radar sensor system (Y page 223).
For further information about the radar sen- sor system; see (Y page 350).
Monitoring range of the sensors
In particular, the detection of obstacles can
be impaired in the case of:
R dirt on the sensors or anything else cover-
ing the sensors
R poor visibility, e.g. due to fog, heavy rain or
snow
R a narrow vehicle travelling in front, e.g. a
motorcycle or a bicycle
R very wide lanes
R narrow lanes
R vehicles not driving in the middle of their
lane
R barriers or other road boundaries
Vehicles in the monitoring range are then not indicated. Blind Spot Assist monitors the area up to
3.0 mbehind your vehicle and directly next to
your vehicle, as shown in the diagram. For this
purpose, Blind Spot Assist uses radar sensors in the rear bumper.
If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may
be indicated, especially if the vehicles are not
driving in the middle of their lane. This may be the case if the vehicles are driving on the inner
side of their lane.
Due to the nature of the system:
R warnings may be issued in error when driv-
ing close to crash barriers or similar solid
lane borders.
R warnings may be interrupted when driving
alongside particularly long vehicles, for
example lorries, for a prolonged time.
The two sensors for Blind Spot Assist are
integrated into the sides of the rear bumper.
Make sure that the bumper is free of dirt, ice
or slush in the vicinity of the sensors. The
radar sensors must not be covered, for exam- ple by cycle racks or overhanging loads. Fol-
lowing a severe impact or in the event of dam-age to the bumpers, have the function of the
radar sensors checked at a qualified special-
ist workshop. Blind Spot Assist may other-
wise not work properly. 198
Driving systemsDriving and parking

Indicator and warning display
Blind Spot Assist is not active at speeds below
approximately 30 km/h. Vehicles in the mon-itoring range are then not indicated. :
Yellow indicator lamp/red warning lamp
If Blind Spot Assist is switched on, indicator
lamp :in the exterior mirrors lights up yel-
low up to a speed of 30 km/h. At speeds
above 30 km/h, the indicator lamp goes out
and Blind Spot Assist is operational.
If a vehicle is detected within the monitoring
range of Blind Spot Assist at speeds above
30 km/h, warning lamp :on the corre-
sponding side lights up in red. This warning
always occurs when a vehicle enters the blind
spot monitoring range from behind or from
the side. When you overtake a vehicle, the
warning only occurs if the difference in speed is less than 12 km/h.
The yellow indicator lamp goes out if reversegear is engaged. Blind Spot Assist is then
deactivated.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.
Collision warning
If a vehicle is detected in the monitoring range
of Blind Spot Assist and you switch on the
corresponding turn signal, a double warning
tone sounds. Red warning lamp :flashes. If
the turn signal remains on, detected vehicles
are indicated by the flashing of red warning
lamp :. There are no further warning tones. Activating Blind Spot Assist
X Make sure that the radar sensor system
(Y page 223) and Blind Spot Assist
(Y page 219) are activated in the on-board
computer.
X Turn the key to position 2in the ignition
lock.
Warning lamps :in the exterior mirrors
light up red for approximately 1.5 seconds
and then turn yellow.
Towing a trailer
If you attach a trailer, make sure that you have
correctly established the electrical connec-
tion. This can be accomplished by checking
the trailer lighting. Blind Spot Assist is then
deactivated. The indicator lamp lights up yel-
low in the exterior mirrors and the Blind
Blind
Spot Assist currently unavailable Spot Assist currently unavailable
See Owner's Manual See Owner's Manual message appears in
the multifunction display.
i You can deactivate the indicator lamps in
the exterior mirrors.
To do so, switch off Blind Spot Assist if:
R the key is in position 2in the ignition
lock.
R the engine is not running.
R the electrical connection to the trailer
has been established.
Lane Keeping Assist General notes
Lane Keeping Assist monitors the area in
front of your vehicle by means of a camera at
the top of the windscreen. Lane Keeping
Assist detects lane markings on the road and
warns you before you leave your lane unin-
tentionally. Driving systems
199Driving and parking Z

:
Lane Keeping Assist camera
If you select km
kmon the on-board computer in
the Display unit Speed-/odometer
Display unit Speed-/odometer func-
tion (Y page 220), Lane Keeping Assist is
active starting at a speed of 60 km/h. If the
miles
miles display unit is selected, the assistance
range begins at 40 mph.
Important safety notes G
WARNING
Lane Keeping Assist cannot always clearly
identify lane markings.
In these cases, Lane Keeping Assist may:
R give an unnecessary warning
R not give a warning
There is a risk of an accident.
Always pay particular attention to the traffic
situation and keep in lane, especially if Lane
Keeping Assist alerts you. G
WARNING
The Lane Keeping Assist warning does not
return the vehicle to the original lane. There is a risk of an accident.
Always steer, apply the brakes or accelerate
the vehicle yourself, especially if Lane Keep-
ing Assist alerts you.
If you fail to adapt your driving style, Lane
Keeping Assist can neither reduce the risk of
an accident nor override the laws of physics. Lane Keeping Assist cannot take into account
road, weather or traffic conditions. Lane
Keeping Assist is only an aid. You are respon- sible for the distance to the vehicle in front, for vehicle speed, for braking in good time,
and for staying in the lane.
Lane Keeping Assist does not keep your vehi-
cle in its lane.
The system may be impaired or may not func-
tion if:
R there is poor visibility, e.g. due to insuffi-
cient 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, dam-
aged or covered, for instance by a sticker in
the vicinity of the camera
R no, or several, unclear lane markings are
present for one lane, e.g. in a construction
area
R the lane markings are worn away, dark or
covered 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
detected
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 road
A warning may be given if a front wheel
passes over a lane marking. It will warn you by means of intermittent vibration in the steer-
ing wheel for up to 1.5 seconds.
Activating Lane Keeping Assist
X Activate Lane Keeping Assist using the on-
board computer; to do so, select Standard Standard
or Adaptive
Adaptive(Y page 219).
If you drive at speeds above 60 km/h and
lane markings are detected, the lane mark-
ings in the assistance graphics display
(Y page 217) are shown in green. 200
Driving systemsDriving and parking

When
Standard 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 ®
.
When Adaptive is selected, no warning vibra-
tion occurs if:
R you have switched on the turn signals. In
this case, 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.
In order that you are warned only when nec-
essary and in good time if you cross the lane marking, the system recognises certain con-
ditions 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 motor-
way.
R the system recognises solid lane markings.
The warning vibration occurs later if:
R the road has narrow lanes.
R you cut the corner on a bend. Towing a trailer
Notes on towing a trailer
Important safety notes G
WARNING
The braking system can overheat if you leave your foot on the brake pedal while driving.
This increases the braking distance and could even cause the braking system to fail. There is
a risk of an accident.
Never use the brake pedal as a footrest. Do
not simultaneously depress both the brake
pedal and the accelerator pedal while driving. 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 the permissible load for a car- rier system is exceeded, the carrier could
come loose from the vehicle and endanger
other road users. There is a risk of an accidentand injury.
Never exceed the permissible noseweight
when using a carrier.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
Trailer towing is not permissible on the fol-
lowing models: R A 45 AMG 4MATIC
R Vehicles with the AMG Sports package
If you exceed the maximum permissible nose- weight of the trailer drawbar on the ball cou-
pling, the following may become damaged:
R your vehicle
R the trailer
R the ball coupling
R the trailer tow hitch
The vehicle/trailer combination could
become unstable.
If the noseweight used is lower than the min- imum permissible noseweight, the vehicle/ Towing a trailer
201Driving and parking Z

trailer combination could also become unsta-
ble.
To avoid hazardous situations:
R make sure to check the noseweight before
each journey.
R use a drawbar noseweight as close as pos-
sible to the maximum noseweight.
R do not exceed the maximum permissible
noseweight.
R do not use a noseweight lower than the
minimum permissible trailer drawbar nose-
weight.
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 man- ufacturer on the vehicle identification plates
and those for the towing vehicle under "Tech-
nical data" (Y page 349).
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 gradi-
ent-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 char-
acteristics. Adapt your style of driving accord-
ingly. Maintain a safe distance. Drive care-
fully.
When towing a trailer, always adjust your
speed to the current road and weather con-
ditions. Do not exceed the maximum permis- sible speed for your vehicle/trailer combina-
tion.
General notes X
When towing a trailer, set the tyre pressure
on the rear axle of the towing vehicle for a
maximum load; see the tyre pressure table
in the fuel filler flap (Y page 321).
Please note that when towing a trailer, PARK-
TRONIC (Y page 182) and Blind Spot Assist
(Y page 197 )availability is limited or not avail-
able at all.
i The height of the ball coupling changes
with the load of the vehicle. If necessary,
use a trailer with a height-adjustable draw-
bar.
You will find fitting dimensions and loads
under "Technical data" (Y page 348).
Driving tips i
Observe the notes on ESP ®
trailer stabi-
lisation (Y page 68).
The maximum permissible speed for vehicle/
trailer combinations depends on the type of
trailer. Before beginning the journey, check
the trailer's documents to see what the max- imum permitted speed is. Observe the legally 202
Towing a trailerDriving and parking

prescribed maximum speed in the relevant
country.
For certain Mercedes-Benz vehicles, the max-
imum permissible rear axle load is increased
when towing a trailer. Refer to the "Technical
data" section to find out whether this applies to your vehicle. If you utilise any of the added
maximum rear axle load when towing a trailer, the vehicle/trailer combination may not
exceed a maximum speed of 100 km/ hfor
reasons concerning the operating permit.
This also applies in countries in which the
permissible maximum speed for vehicle/
trailer combinations is above 100 km/h.
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
to when driving without a trailer and it will
consume more fuel.
Change into a lower gear in good time on long
and steep downhill gradients. For vehicles
with automatic transmission, you need to
have selected manual drive program
M(Y page 156).
i This also applies if you have activated
cruise control, SPEEDTRONIC or DIS-
TRONIC PLUS.
This will use the braking effect of the engine,
so less braking will be required to maintain
vehicle speed. This relieves the load on the
brake system and prevents the brakes from
overheating and wearing too quickly. If you
need additional braking, depress the brake
pedal repeatedly rather than continuously.
i Briefly depressing the accelerator pedal
on downhill gradients while the manual
drive program Mis temporarily activated
(vehicles with automatic transmission): the automatic transmission may switch back to
the last active automatic drive program Eor
S. The automatic transmission may shift to a higher gear. This can reduce the engine'sbraking effect. Driving tips If the trailer swings from side to side:
X Do not accelerate.
X Do not countersteer.
X Brake if necessary.
R Maintain a greater distance from the vehi-
cle in front than when driving without a
trailer.
R Avoid braking abruptly. If possible, brake
gently at first to allow the trailer to run on.
Then, increase the braking force rapidly.
R The values given for gradient-climbing
capabilities from a standstill refer to sea
level. When driving in mountainous areas,
note that the power output of the engine,
and consequently the vehicle's gradient-
climbing capability, decrease with increas-
ing altitude. Folding out the ball coupling
G
WARNING
If you release the ball coupling or it does not
engage correctly when folding in, it will swing out. Within pivoting range of the ball coupling,
there is an increased risk of an accident and
injury.
Only release the ball coupling if the pivoting
range is unobstructed. Always make sure that the ball coupling engages when folding in.
Before you can tow a trailer with your vehicle, you must fold out the ball coupling.
The release wheel is located behind the left-
hand side trim panel in the boot. Towing a trailer
203Driving and parking Z

X
To open the cover: turn handle:anti-
clockwise and fold down cover ;and
remove it. X
Pull out release wheel =.
X Turn release wheel =anti-clockwise as far
as it will go.
The ball coupling disengages and folds out
behind the rear bumper. Indicator lamp ?
flashes. G
WARNING
If the ball coupling is not correctly engaged,
the trailer can detach. There is a risk of an
accident. Always engage the ball coupling as described.
X Pull the ball coupling in the direction of the
arrow until it engages in a vertical position.
Indicator lamp ?goes out. The power
socket folds down automatically.
The multifunction display shows the
Check Check trailer
trailer hitch
hitchlock
lockdisplay mes-
sage until the ball coupling is engaged.
X Remove the protective covering from the
ball coupling and store it in a safe place.
X Make sure that the ball of the ball coupling
is clean and that it is either greased or dry
(grease free), depending on the instruc-
tions for the trailer. Coupling up a trailer
X Make sure that the transmission is in posi-
tion P.
X Apply the electric parking brake.
X Position the trailer level behind the vehicle.
X Couple up the trailer.
X Establish the electric connection between
the vehicle and the trailer.
X Check that the trailer lighting system is
working.
A trailer that is connected is recognised
only when the electrical connection is
established correctly and when the lighting system is working properly. The function of
other systems, such as ESP ®
or PARK-
TRONIC also depends on this. Uncoupling a trailer
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. 204
Towing a trailerDriving an
d parking

!
Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could be damaged by the rebound- ing of the overrun brake.
! Remove the installed adapter cable
before folding in the ball coupling. Other-
wise, damage may occur to the rear
bumper and the adapter cable.
X Make sure that the transmission is in posi-
tion P.
X Apply the electric parking brake.
X Secure the trailer against rolling away.
X Remove the trailer cable and decouple the
trailer. Folding in the ball coupling
G
WARNING
If you release the ball coupling or it does not
engage correctly when folding in, it will swing out. Within pivoting range of the ball coupling,
there is an increased risk of an accident and
injury.
Only release the ball coupling if the pivoting
range is unobstructed. Always make sure that the ball coupling engages when folding in.
X Fold the ball coupling back in if you are not
using the trailer tow hitch.
X Place the protective covering on the ball
coupling.
The release wheel is located behind the left-
hand side trim panel in the boot. X
To open the cover: turn handle:anti-
clockwise and fold down cover ;and
remove it. X
Pull out release wheel =.
X Turn release wheel =anti-clockwise as far
as it will go.
The ball coupling disengages and folds out
behind the rear bumper. Indicator lamp ?
flashes. X
Press the ball coupling in the direction of
the arrow until it engages behind the
bumper.
Indicator lamp ?goes out and the mes-
sage in the multifunction display disap-
pears. Trailer power supply
! You can connect accessories with a
power rating of up to 240 W to the perma-
nent power supply and with a power rating of up to 180 W to the power supply that is
switched on via the ignition lock. Towing a trailer
205Driving and parking Z