MERCEDES-BENZ S550 4MATIC 2008 W221 Owner's Manual

430 Controls in detail
Driving systems
DISTRONIC Plus lever
The DISTRONIC Plus system is operated by
means of the DISTRONIC Plus lever.
1Setting current or higher speed
Adjustment in 1 mph or 5 mph
increments
2Setting current or lower speed
Adjustment in 1 mph or 5 mph
increments
3Canceling DISTRONIC Plus
4Activating DISTRONIC Plus or resum-
ing to last set speed
5Setting target distanceActivating DISTRONIC PlusYou can activate DISTRONIC Plus when:

you are driving slower than 20 mph and
DISTRONIC Plus has detected a vehicle
ahead of you

you are driving above 20 mph
If DISTRONIC Plus has not been activated
after pressing the DISTRONIC Plus lever,
you will see the message: “DISTRONIC
PLUS - - - mph” in the multifunction display.
In the following cases you cannot activate
DISTRONIC Plus:

up to 2 minutes after starting the en-
gine

if the engine is switched off

if you step on the brake pedal while
driving

the vehicle is secured with the elec-
tronic parking brake

if the gear selector lever is in
positionP, R, or N
Warning!G
When DISTRONIC Plus is braking, the brake
pedal is retracted (i.e. depressed automati-
cally). The pedals’ range of motion must not
be impeded by any obstacles:

Do not place any objects in the footwell.

Make sure that the floor mats and car-
pets are securely in place.

Do not rest your foot underneath the
brake pedal, as it could otherwise be
trapped.
You could otherwise cause an accident and
injure yourself and others.
Warning!G
When DISTRONIC Plus is switched on, the
vehicle can be braked. You should therefore
switch off DISTRONIC Plus if the vehicle
must be towed.
iThe maximum speed you can set is
120 mph.

431 Controls in detail
Driving systems

if ESP® is switched off

if the hood is open

if the driver’s door is open and the driv-
er has not fastened his or her seat belt

if the radar sensors are switched off
(
page 282).
Switching on while driving
Tap DISTRONIC Plus lever up1 or
down2 until desired speed is set.
DISTRONIC Plus is switched on.
or
Pull DISTRONIC Plus lever briefly in di-
rection of arrow4 to call up speed
last set (
page 435).
DISTRONIC Plus is switched on.
Take your foot off the accelerator ped-
al.
Your vehicle adapts its speed to the ve-
hicle ahead, observing the set speed as
a maximum value.Switching on when approaching a sta-
tionary vehicle
If the vehicle in front of you is stationary,
you can only switch on DISTRONIC Plus if
your vehicle is also at a standstill.
Tap DISTRONIC Plus lever up1 or
down2 until desired speed is set.
DISTRONIC Plus is switched on.
or
Pull DISTRONIC Plus lever briefly in di-
rection of arrow4 to call up speed
last set (
page 435).
DISTRONIC Plus is switched on.
iUnder 20 mph, you can only switch on
DISTRONIC Plus if the vehicle ahead of you has
been detected and is shown on the multifunction
display. If you no longer see the vehicle in front
of you on the multifunction display and if it is no
longer detected because it has changed lanes,
for example, DISTRONIC Plus switches off and
you will hear a signal.
iIf you do not completely lift your foot off the
accelerator pedal, the message“DISTRONIC
PLUS override” appears on the multifunction dis-
play. The distance to a slower-driving vehicle will
not be set. You will drive at the speed you dictate
by pressing the accelerator pedal.
iIt is helpful to switch on the DISTRONIC Plus
display in the instrument cluster (
page 428)
since you can only switch on DISTRONIC Plus un-
der a speed of 20 mph when a vehicle has been
detected in front of you.
iYou can adjust the set speed using the
DISTRONIC Plus lever and the target distance
using the distance setting switch on the
DISTRONIC Plus lever (
page 436).

432 Controls in detail
Driving systems
Starting off
When the vehicle in front of you starts off:
Remove your foot from the brake
pedal.
Pull DISTRONIC Plus lever briefly in di-
rection of arrow4.
or
Briefly step on the accelerator pedal.
Your vehicle starts off and adapts its speed
to the vehicle in front of you.Driving
If no vehicle is driving ahead of you,
DISTRONIC Plus functions like the cruise
control (
page 419).
When DISTRONIC Plus detects that the ve-
hicle in front of you is driving more slowly,
it brakes the vehicle in order to keep the
distance specified by you.
When DISTRONIC Plus detects that the ve-
hicle in front of you is driving faster, the ve-
hicle accelerates up to the set speed.Stopping
iIf DISTRONIC Plus is switched off,
PRE-SAFE® Brake* (page 76) will warn of an
impending collision if this function has been ac-
tivated with the instrument cluster control sys-
tem (
page 279).
Warning!G
When you step on the brake pedal, you
switch off DISTRONIC Plus except when the
vehicle is at a standstill. DISTRONIC Plus will
no longer brake your vehicle. You are always
responsible for maintaining a distance from
other vehicles, observing road speeds and
braking well in advance.
Warning!G
DISTRONIC Plus’s braking effect is canceled
and the vehicle can start to roll if

DISTRONIC Plus is switched off using
the DISTRONIC Plus lever

you accelerate

the system or the power supply is mal-
functioning, e.g. due to battery failure

the electrical components in the engine
compartment or the fuses have been
manipulated

the battery is disconnected


433 Controls in detail
Driving systems
When DISTRONIC Plus detects that the ve-
hicle in front of you is stopping, the vehicle
brakes until it also stops.
Once DISTRONIC Plus has stopped your
vehicle and it is at a standstill, it remains
stationary; the brake pedal does not need
to be depressed.Setting the current speed
Accelerate or decelerate to the desired
speed.
Briefly lift the DISTRONIC Plus lever in
the direction of arrow1 or depress in
the direction of arrow2.
DISTRONIC Plus is activated and the
current speed is set.
Remove your foot from the accelerator
pedal.Setting a higher speed
You can increase the set speed in two stag-
es.
Adjustment in 1 mph increments
Briefly lift the DISTRONIC Plus lever to
the resistance point in direction of
arrow1 (
page 430).
Release the DISTRONIC Plus lever.
The vehicle speed increases in incre-
ments of 1 mph.
Warning!G
Never get out of the vehicle while
DISTRONIC Plus is switched on!
DISTRONIC Plus must never be operated or
switched off by passengers or from outside
the vehicle.
DISTRONIC Plus is not a substitute for the
electronic parking brake and may not be
used for parking.
When you get out of the vehicle or switch off
the engine, deactivate DISTRONIC Plus and
secure the vehicle from rolling away by en-
gaging the electronic parking brake.
iAfter a short while, your vehicle is secured in
place by the electronic parking brake so that the
operating brake can be relieved of load.
iDepending on the following distance set us-
ing the distance setting switch on the
DISTRONIC Plus lever, your vehicle will stop ap-
proximately 13.1 ft away from the vehicle in
front of you.
iIf you do not take your foot off of the accel-
erator completely, the following message
“DISTRONIC PLUS override” will appear in the
multifunction display.
The distance to a slower moving vehicle in front
of you will not be set. Your vehicle speed will
then be determined only by the accelerator ped-
al position.
iThe set speed value is increased in 1 mph in-
crements each time you lift the DISTRONIC Plus
lever to the resistance point.

434 Controls in detail
Driving systems
Adjustment in 5 mph increments
Briefly lift the DISTRONIC Plus lever
past the resistance point in direction of
arrow1 (
page 430).
Release the DISTRONIC Plus lever.
The vehicle speed increases in incre-
ments of 5 mph.Setting a lower speed
You can reduce the speed in two stages.
Adjustment in 1 mph increments
Briefly press the DISTRONIC Plus lever
down to the resistance point in direc-
tion of arrow2 (
page 430).
Release the DISTRONIC Plus lever.
The vehicle speed decreases in incre-
ments of 1 mph.Adjustment in 5 mph increments
Warning!G
You can increase the vehicle speed in 5 mph
increments. When using this feature, keep in
mind that it may take a brief moment until
the vehicle has reached the set speed.
Increase the vehicle speed to a value that
the prevailing road conditions permit. Other-
wise, sudden and unexpected acceleration
of the vehicle could cause an accident
and/or serious injury to you and others.
iThe set value is increased in 5 mph incre-
ments each time you lift the DISTRONIC Plus le-
ver past the resistance point.
iThe new speed is set and the vehicle will ac-
celerate. Keep in mind that it may take a brief
moment until the vehicle has reached the set
speed.
iWhen you use the DISTRONIC Plus lever to
decelerate, the brake system will automatically
brake the vehicle if the engine’s braking power
does not brake the vehicle sufficiently.
iThe set value is decreased in 1 mph incre-
ments each time you press the DISTRONIC Plus
lever down to the resistance point.
Warning!G
You can decrease the vehicle speed in
5 mph increments. When using this feature,
keep in mind that it may take a brief mo-
ment until the vehicle has reached the set
speed.
Decelerate the vehicle speed to a value that
the prevailing road conditions permit. Other-
wise, sudden and unexpected deceleration
of the vehicle could cause an accident
and/or serious injury to you and others.

435 Controls in detail
Driving systems
Briefly press the DISTRONIC Plus lever
down past the resistance point in
direction of arrow2 (
page 430).
Release the DISTRONIC Plus lever.
The vehicle speed decreases in incre-
ments of 5 mph.Setting to last stored speed (“Resume”
function)
Briefly pull the DISTRONIC Plus lever in
the direction of arrow4 (
page 430).
DISTRONIC Plus is set to the last
stored speed.
DISTRONIC Plus resumes the last set
speed or if no speed is stored, it will set
and store the current speed.
Remove your foot from the accelerator
pedal.Deactivating DISTRONIC Plus
There are several ways to deactivate the
DISTRONIC Plus system:
Briefly tip the DISTRONIC Plus lever in
the direction of arrow3 (
page 430).
or
Step on the brake pedal.
DISTRONIC Plus will be deactivated.
The last speed set will be stored into
memory.
DISTRONIC Plus deactivates automatically
when:

the vehicle is secured with the elec-
tronic parking brake

the vehicle speed is below 20 mph and
no preceding vehicle is detected

the ESP® is in operation or switched off
with the ESP® switch (page 73)

you set the automatic transmission
toP, R, or N while driving
iThe set value is decreased in 5 mph incre-
ments each time you press the DISTRONIC Plus
lever down past the resistance point.
iThe new speed is set and the vehicle will de-
celerate. Keep in mind that it may take a brief
moment until the vehicle has reached the set
speed.
Warning!G
The speed stored in memory should only be
set again if prevailing road conditions per-
mit. Possible acceleration or deceleration
differences arising from returning to preset
speed could cause an accident and/or seri-
ous injury you and others.
iUpon switching off the engine, the last
stored speed is deleted.
iThe last stored speed is deleted when you
turn off the engine.

436 Controls in detail
Driving systems

the radar sensors are switched off
(
page 282)

the vehicle rolls backward
The segments in the multifunction display
go out, an acoustic signal sounds, and the
message “DISTRONIC PLUS Off” appears in
the multifunction display for approximately
5 seconds.
If the vehicle has been stopped by
DISTRONIC Plus and a malfunction occurs
in the system, the message “Brake immedi-
ately” will appear on the multifunction dis-
play. Step on the brake immediately to
prevent the vehicle from rolling.
DISTRONIC Plus is then switched off and
the message disappears.Setting the following distance in
DISTRONIC Plus
You can set the specified following dis-
tance for DISTRONIC Plus by varying the
time setting between 1.0 and 2.0 seconds.
Using this time setting and the current set
speed of your vehicle, DISTRONIC Plus cal-
culates and sets the required following dis-
tance to the vehicle ahead. The set
distance will be shown in the multifunction
display.
Warning!G
DISTRONIC Plus switches off and releases
the brakes when the vehicle decelerates be-
low the minimum speed of 20 mph by oper-
ation of the system unless DISTRONIC Plus
detects a vehicle directly ahead of you. At
that time the driver must apply the brakes in
order to reduce vehicle speed further or
bring it to a stop.
!Setting the automatic transmission toN
while driving cancels the DISTRONIC Plus. How-
ever, the automatic transmission should not be
set toN while driving except to coast when the
vehicle is in danger of skidding (e.g. on icy
roads).
iDepressing the accelerator pedal does not
deactivate DISTRONIC Plus. After brief accelera-
tion (e.g. for passing), DISTRONIC Plus will re-
sume the last speed set.
Warning!G
It is up to the driver to exercise discretion to
select the appropriate setting given road
conditions, traffic, driver’s preferred driving
style and applicable laws and driving recom-
mendations for safe following distance.

437 Controls in detail
Driving systems
The distance setting switch for the target
distance is located on the DISTRONIC Plus
lever.
1Distance setting switch for target dis-
tance
2To increase target distance
3To decrease target distance
Increasing distance
Increasing the distance setting causes
DISTRONIC Plus to maintain a greater fol-
lowing distance to the vehicle ahead.
Move distance setting switch 1 in di-
rection 2.Decreasing distance
Decreasing the distance setting causes
DISTRONIC Plus to maintain a shorter fol-
lowing distance to the vehicle ahead.
Move distance setting switch 1 in di-
rection 3.
Driving with DISTRONIC Plus
This section describes a number of driving
situations where special precaution is re-
quired on the part of the driver. Be pre-
pared to brake in such situations which will
deactivate the DISTRONIC Plus system.
Warning!G
DISTRONIC Plus works to maintain the
speed selected by the driver unless a mov-
ing obstacle proceeding directly ahead of it
in the same travel direction is detected (e.g.
following another vehicle ahead of you at a
distance set by DISTRONIC Plus).
This means that:

Your vehicle can pass another vehicle
after you change lanes.

While in a sharp turn or if the vehicle in
front is in a sharp turn, DISTRONIC Plus
could lose sight of a vehicle traveling in
front of it, then your vehicle could accel-
erate to the previously selected speed.
DISTRONIC Plus regulates only the distance
between your vehicle and those directly
ahead of it. It may not register stationary ob-
jects in the road, e.g.:

a stopped vehicle in a traffic jam

a disabled vehicle

an oncoming vehicle
The driver must always be on the alert, ob-
serve all traffic and intercede as required by
steering or braking the vehicle.
Warning!G
DISTRONIC Plus should not be used in
snowy or icy road conditions.

438 Controls in detail
Driving systems
The most likely cause for a malfunctioning
system is a dirty sensor (located behind
the hood grille), especially at times of snow
and ice or heavy rain. In such a case,
DISTRONIC Plus will switch off, and the
message:
“DISTRONIC PLUS
currently unavailable
See Oper. Manual”
appears in the multifunction display.
For cleaning and care of the
DISTRONIC Plus sensor, see “Cleaning the
DISTRONIC Plus*/ PRE-SAFE
® Brake*
system sensors (USA only)” (
page 589).Another cause might be that the radar sen-
sors have been manually switched off in
the instrument cluster control system.
Please verify that the radar sensors are
switched on (
page 282).Turns and bends
In turns or bends, DISTRONIC Plus may not
detect a moving vehicle in front, or it may
detect one too soon. This may cause your
vehicle to brake late or unexpectedly.
iIf the message:
“DISTRONIC PLUS
currently unavailable
See Oper. Manual”
disappears during driving and the last speed
stored flashes for approximately 5 seconds, the
dirt (e.g. slush) has dissolved; DISTRONIC Plus is
again available.

439 Controls in detail
Driving systems
Offset driving
A vehicle traveling in your lane but offset
from your direct line of travel may not be
detected by DISTRONIC Plus. There will be
insufficient distance to the vehicle ahead.Lane changing
DISTRONIC Plus has not yet detected the
vehicle changing lanes. There will be insuf-
ficient distance to the lane-changing vehi-
cle.Narrow vehicles
Because of their narrow profile, the vehi-
cles traveling near the outer edge of the
lane have not yet been detected by
DISTRONIC Plus. There will be insufficient
distance to the vehicles ahead.