Adaptive cruise control Speed and distance
control system
Description
Applies to vehicles: with adaptive cruise cont rol
The adaptive cruise control driver assistance
program is a combined speed and distance
control system .
Fig . 126 Front bu mper: Pos itio n of r adar sen sor (not
vi sibl e from out side)
Adapt ive cruise control can he lp ma ke driv ing
more relaxed and less tiring , particularly dur
i n g long trips on interstates or other hig hways
that are genera lly st raight. The system can al
so ass ist in stop and go traffic .
The adaptive cruise co ntrol works within a
speed range be tween 0 and 95 mph (150 km/
h). Set ACC to maintain a constant , legal trav
el speed between 20 and 95 mph (30 -150
km/h) that is appropriate for prevailing traffic
conditions. Select a following distance to the
veh icle ahead and ACC will adjust your speed
to maintain that d istance down to a stop . At a
speed below 20 mph (30 km/h), the min imum
speed setting of 20 mph (30 km/h) will be se l ected automati ca lly.
Adaptive cruise control has technical limita
tions that you must know, so p lease read th is
section carefully , understand how the system
wo rks and use it properly at a ll times.
How does it work?
You can operate the adaptive cruise control
using the lever on the steering wheel column
c::> page 116, How is the speed stored? and
Ad apti ve crui se control 11 3
c::> page 118, How is the distance (time inter
val) set? .
Driver information
Important information is brought up in the
speedomete r and in the instr ument clus ter
display as the vehicle is being driven
c::> page 120, Driver informat ion .
What is important for you to know
The adaptive cru ise contro l is set w ith system
spe cified lim its; that is, as a driver, you will
have to adjus t the speed and distance to the
vehicle ahead in some instances
c:> page 124,
Driver intervention prompt
and c::> page 125,
System limitations.
A WARNING
Imp roper use of the adaptive cruise con
trol can cause collisions, other accidents
and serious personal injury.
- Always remember that the adaptive cru ise contro l has limits -it will not slow
the vehicle down or ma inta in the set d is
tance when you dr ive towards an obsta
cle or someth ing o n or nea r the road that
is not movi ng, such as ve hicles stopped
in a tra ffic jam, a sta lled or d is ab led vehi
cle.
- Always remembe r that the adaptive
cru ise con tro l canno t detect a vehi cle
that is driving towards yo u in your traffic
lane and that it cannot detect narrow
vehicles s uch as motorcycles and bicy
cles.
- Never drive at speeds that are too fast
for traffic, road and weather conditions.
- Never follow a vehicle so closely that yo u
cannot stop your vehicle safely. The
adaptive cruise control cannot s low or
brake the vehicle safely when you follow
another vehicle too close ly. Always re
membe r that the adaptive cruise control
has a braking powe r th at is o nly about
30% of the veh icle 's maxim um braking
ab ility. The a uto mat ic bra kin g f unction
canno t bring the veh icle to a s udden or
emergency stop . Always be p repared to
-
that must have a certain size. The system re
sponds only after the distance measurement has been made. If a measurement is not pos
sible, the system cannot respond and w ill not
react to a vehicle or someth ing else up ahead.
Open road
When the road is clear, the adaptive cruise
contro l works like cr uise control. It maintains
a constant target speed specified by the driv
er.
Driving in traff ic
If a slowe r vehicle driving ahead is detec ted,
the adaptive cruise contro l decelerates (within
the limits of the system)
¢ page 124, Driver
intervention prompt
and c:> page 125, System
limitations
to its speed and after adjust ing,
tr ies to maintain the set distance from the ve
h icle ahead. The vehicle may temporarily drive
slower than the set speed while adjust ing
¢ & in Description on page 113 .
If the vehicle in front accelerates, adaptive
cruise control also accelerates up to the speed
that you have set.
If the vehicle ahead slows to a stop, ACC will
slow your vehicle down and to a complete
stop if this is possible w ith in the system's lim
its and capabilities . ACC will not make an
emergency stop. The text message
ACC off :
manual c ontrol!
appears in the instr ument
cluster display . Once the veh icle stops, you
must depress the brake pedal to prevent the
vehicle from moving forward or "creeping". Depressing the brake pedal turns
off ACC.
When the veh icle ahead accelerates you can
reactivate ACC
¢ page 118, as soon as your
ve hicle has reached a speed of 1 mph (2 km/
h) .
Situ ation s re quiring dri ver int ervention
In some s ituations you w ill have to use the
footbrake to s low the vehicle down in order to
keep a safe distance from vehicle in front of
you or to avo id a rear-end coll is ion. In this sit
uation, a symbol appears and a warning tone
sounds
¢ page 124.
Ada pti ve crui se control 115
Passing another vehicle
If you move in to the passing lane and no ve hi
cle is detected ahead, the adaptive cr uise con
trol acce le rates to the speed you have set and
maintains it.
Overr iding ACC
You can in cr ease yo ur speed at a ny time by
stepping on the accelera tor ped al. A fter you
release the accelerator peda l, the system ad
justs back down to the speed you prev ious ly
set .
Reducing stopp ing distance
If the radar sensor detects that the d istance
to the vehicle a head is less than de fined m ini
mum distance, the brakes are automatically
prepared fo r emergency braking by the driver .
The brake pads are moved very close to the brake d iscs without actually braking the vehi
cle. This brake assistant feature reacts more
quick ly to the dr ive r's brak ing, and also works
when adapt ive cruise control is off . The stop
ping distance is reduced as a result of th is ad
vance brake p reparation . Th is fun ction does
not perform any emergency b rak ing mane u
vers by itse lf; the dr iver mus t always apply the
brakes.
A WARNING
If ACC initiates a braking maneuver, the brake pedal w ill be retracted. Inter ference
with the brake peda l can prevent ACC from
slowing the veh icle down and cause a
crash and serious personal injury.
- Never put anything in the driver's foot
well or let anyth ing fall into it. An object
in the driver's footwe ll can interfe re with
the peda ls and prevent the acce le rator
from being used to override ACC or pre
vent ACC from being switched off when
the brake pedal is depressed and also
prevent the vehicle from being slowed
down or stopped .
- On ly use floor mats that keep the area
around the peda ls free and that can be
securely fastened to the footwell .
-
116 Adapti ve crui se control
-Never drive with you r foot underneath
t h e brake pedal.
- Always read and heed the information
and WARNINGS
c:;, .&. in Description on
page 113.
A WARNING
- Never rely on the distance control fea
ture of ACC alone to prevent rear-end col
lisions . Always be prepared to brake and
take evasive action to avoid collisions and other acc ident situations.
- Never allow the clos ing speed between
yo u and other vehicles to be so h igh that
the adaptive c ruise control may not be
able to slow your vehi cle safe ly. If clos
ing speed is too high, you m ust app ly the
brakes yourself to reduce the risk of a
rear-end crash.
(D Tips
Please note that t he amo un t of a ccelera
tion the adapt ive cr uise control uses de
pends on the Distance setting selected .
DISTANCE 1 g ives you acce lerat ion that is
dynamic and sporty. DISTANCE 4, on the
other hand, gives more moderate acce lera
tion. For more information about the time
intervals
c:;, page 118 , How is the distance
(time interval) set? .
-Please note that if the adaptive cruise
control has begun braking the vehicle
and the d river chooses to brake the vehi
cle add itiona lly, t he b rakes may fee l
"h ard". This is simply due to the pressure
b uild- up of the initial b raking.
- Adaptive cruise control is sw itched off af
te r pressing the footbrake. The speed
saved u p this poin t can be resumed. To
res ume the saved speed, release the
b rake pedal and p ull th e control leve r to
ward you
c:;, page 118 , Turning adaptive
cruise control off temporarily .
Switching the system on and off
Applies to vehicles: with adaptive cruise contro l
Fig. 128 Control lever: Sw itching on and off
S w itching the sy stem on
.,. Pull the lever to position (D c::> fig. 128 .
Switching the system off
.,. Pres s th e lever to pos it ion @ (latched).
How is the speed stored?
Applies to vehicles: wit h adaptive cruise contro l
,' ts ~:_" ';;;", ' , E Sl'EEO CANCELU
. T ,0. -ON ... . RESUME~
Fig. 1 29 Co ntrol lever: Storing s peed
With the sy stem switched on the speed is
stored as follows:
• Drive at the speed you want .
.,. Press the
ISET I button c:;, fig. 129 to store
the desired speed.
After the
ISE TI button is re leased, the current
speed is stored and maintained . If you are
driv ing at a speed below 20 mph (30 km/ h),
the minimum speed setting of 20 mph
(30 km/h) will be set .
The saved speed is now shown in the LED d is
play in the speedometer by one or two illumi
nated red light d iodes
c::> page 121. At the
same time, the saved speed is also shown for ..,.
a short time in the Information line
¢ page 122.
@ Tips
For safety reasons, the stored speed is
erased when the ignition or the ACC is
turned off.
Changing stored speed
Applies to vehicles : with adaptive cruise co ntrol
The speed can be changed without touching
the accelerator or brake pedal .
Fig. 130 Contro l leve r: Changing speed
Inc re as ing speed
• Press the lever briefl y upwards 0
9 fig. 130. USA models: the speed increases
by about 2.5 mph. Canada models : speed
will increase by one mark on the speedome
ter sca le .
• Press the lever upwards
0 and hold it. As
long as you ho ld the control switc h down,
the lig ht diode display in t he speedome ter
L E D display in the speedometer moves for
ward and the speed is increased.
R educing speed
• Press the lever briefly downwards Q. USA
models: the speed decreases by 2.5 mph .
Canada models: speed w il l decrease by one
mark on the speedometer scale.
• Press the lever downwards
O and hol d it.
As long as you hold the control sw itch down,
the lig ht diode display in the speedometer
LED display moves backward and the speed
is reduced .
After releasing the control switch, the system regulates the speed to the va lue just set.
Ad apti ve crui se control 11 7
After each adjustment, the newly-set speed is
shown for a short time in the Information line
9page 122 .
_& WARNING
Improper use of the adaptive cruise con
trol features and inattent ion can lead to an
accident causing ser ious personal injury.
- It is dangerous to use the "RES UME" fea
ture when the prev iously set speed is too
high for existing road, traff ic or weather
conditions.
- Always read and heed the information
and WARNINGS
¢.&. in Description on
page
113 .
(D Tips
You can increase your speed at any time by
stepp ing on the accelerato r pedal. After
you release the acce lerator pedal, the sys
tem adjusts back down to the speed you
p reviously set . A new desired speed can be
stored a t any time by press ing the
!SET I
button 9page 116, fig. 12 9.
-
118 Adaptive cruise control
Turning adaptive cruise control off
temporarily
Applies to vehicles: with adaptive cruise co ntrol
In some situations it makes sense to turn
adaptive cruise control off temporarily.
®
Fig. 131 Con tro l lever : Turning adapt ive cruise co ntro l
off tempo rarily
Fig. 132 D isplay in the speedomete r
Turning control off temporarily
" To shut off the control with the save func
t ion, either depress the brake pedal, or
" Press the lever in the direction of the arrow
@qfig .131 .
How is the distance (time interval) set?
Applies to vehicles: with adaptive cruise co ntrol
Distance can be set in four stages.
Fig. 133 Contro l lever: Setting d istance
Reactivating control
" To resume the speed and distance control,
release the brake pedal and press the lever
in the direction of the arrow@.
Display in the speedometer
@ Current vehicle speed~ fig. 132
@ Saved speed
As long as a speed is saved the set desired
speed will be displayed in the LED display in
the speedometer by one or two illuminated
red light diodes . When the control function is
resumed the adaptive cruise control acceler
ates to reach the desired speed if no slower
vehicle ahead is detected.
&_ WARNING
Improper use of the adaptive cruise con
trol can cause collisions, other accidents
and serious personal injuries.
- Never resume the stored speed if the
speed is too high for prevailing road,
traffic or weather conditions .
(0 Tips
When the system is turned off temporari
l y, the speed set at that time is stored.
Increasing distance
-
" Push the slider switch once to the right 0
q fig. 133 . The distance current ly set is
shown for 3 seconds in the instrument clus
ter display.
" Push the slider switch
again to the right 0
to increase the distance by one step. ..,.
120 Adapti ve crui se control
_&. WARNING
-
Following other vehicles too closely in
creases the risk of a crash and serious per
sonal injury .
- Following other vehicles too closely, par
ticu larly at higher speeds increases the
risk of coll is ions and serious personal in
jury.
- Setting short distances to the traffic
ahead reduces the time and distance
available to bring your vehicle to a safe
stop and makes it even more necessary
to pay close attention to traffic .
- Always select a speed and distance to
traffic ahead that is safe and appropriate
under the prevailing traff ic, road, weath
er and lighting conditions.
- Never rely on the distance control fea
ture of ACC a lone to prevent rear-end col
lis ions. Always be prepared to b rake and
take evasive act io n to avoid co llisions
and other ac cident situations.
- Never allow the clos ing speed between
yo u a nd other vehicles to be so h igh that
the adaptive cruise control may not be
able to slow your vehicle safe ly . If clos
ing speed is too high, yo u m ust app ly the
brakes yourself to reduce the risk of a
rear-end crash.
- Always select a greater following dis
tance to the veh icle ahead on wet roads
than on dry roads.
- Always read and heed the information
and WARNINGS
¢ &. in Description on
page 113.
(D Tips
The distance setting is reset to the factory
default
DIS TANCE 3 the next time the ig
nition is turned on.
Driver information
Displays in the instrument cluster
Applies to veh icles: w ith adaptive cruise contro l
Depending on the driving situation, driver in
formation is displayed in the instrument clus
ter .
Fig . 1 34 Overview ins tr u me nt cluster
@ Speedometer and indica to r li ght d isp lay
@ Display in the instrument cluster
@ Speedometer and indi cato r light
display
Important information concerning vehicle op
eration with adaptive cruise control is shown
in display a rea @. The desired speed you set is
i ndica ted in the speedometer (L ED lights
aro und the edge).
T he ind icator lights show whether the system
has detected a vehicle trave ling ahead .
@ Display in the in strument cluster
In display area @ information from the navi
gation system* and the tr ip computer is dis
played in addition to informat ion about adap
t ive cru ise control.
You can select among the different informa
t io n by repeated brief taps on the
I RESET I but
ton on the w indshie ld w iper lever
c::> page 25,
Operation .
Certain pieces of information in the bottom
part of the d isplay are not shown permanent
ly . Information is displayed only if you set or
change the speed setting, change the time in
te rva l, when messages are disp layed or if the
adaptive cruise contro l is turned off for safety
reasons .
Display in the speedometer
Applies to vehicles: with adaptive cruise control
Fig. 135 D isplay in the speedomete r
Des ired spe ed
The desired speed set by the driver is dis
p layed by a red LED.
If the desi red speed was set between two
lines on the speedometer using the
I SETI but
ton, the two closest light emitting diodes will
come on <=>
fig. 135.
The system a llows only speeds to be set be
tween 20 to 95 mph (30 to 150 km/h) to be
set. This speed range is faint ly illuminated in
the speedometer (LED lights).
Ind icator light s (symbol s)
-- Open road :
The indicator light _
shows that ACC is active and that no moving
vehicle has been detected with in range of the radar sensor up ahead in your lane of
travel. The set speed is maintained.
- - Driving in tr aff ic: The indicator
light - shows that a vehicle moving in
your lane of travel has been detected up
front in your lane of travel. Your speed is ad
justed according to the speed of the vehicle
up front . ACC accelerates and brakes auto
matically within the system's capabilit ies .
-- Driver int erv ent ion prompt: The
red flashing warning light- means
Reque st for dri ver to assum e co ntr ol. You
as the dr iver must slow the vehicle with the
f oot brake. The symbol - tells you
t h at the adaptive cruise co ntrol is not able
to slow the vehicle down enough to keep a
enough distance to the vehicle in front of
you. A warning tone will also sound when
Ad apti ve crui se control 121
the symbol appears. For more information
about the driver intervention prompt
r::!) page 124.
_& WARNING
Improper use of the adaptive cruise con
trol features and inattention can lead to a
crash and serious personal injury.
- Never allow the closing speed between
you and othe r vehicles to be so high that
the adaptive cruise contro l may not be
able to slow your vehicle safely. If clos
ing speed is too high, you must apply the
brakes yo urself to reduce the risk of a
rear-end crash.
- Always select a greater following d is
tance to the vehicle up ahead on wet
roads than on dry roads.
- Always read and heed the information
and WARNINGS <=>
& in Description on
page 113 .
(D Tips
-If you use the accelerator to go faste r
t han t he speed of the vehicle ahead of
you, the dr iver intervention prompt will
not be accompan ied by a warn ing tone.
- If the speed you previously set is exceed
ed, the indicator light in the speedome
ter will switch off.
Display in the instrument cluster
Appl ies to vehicles: wit h adaptive cruise control
F ig. 136 D isp lay in the instrument cluster
-
Scroll through the available information dis
plays by br iefly tapp ing the
I RESET ! button at
the end of the windshield wipe r lever. You can ..,.
122 Adaptive cruise control
select information from the trip computer,
navigation system* or adaptive cruise control.
@ Vehicle symbol
@ Distance
© Status
@Vehicle symbol
The vehicle symbol indicates whether the sys
tem has detected an object traveling in front .
-Vehicle outline: Open road, no vehicle
ahead.
- White vehicle: A vehicle is detected ahead.
-Red vehicle : Request for driver to assume
control.
@ Distance
Using the arrows and scale, you can detect
how far it is to the vehicle in front of you.
- Open road: No arrow appears when the ve
hicle is on an open road and there is no vehi
cle ahead.
- Driving in traffic: If a vehicle is detected
ahead, the arrow moves on the scale. The
green area represents the distance set.
When approach ing slow ly, the arrow moves
from the
gray zone to the green zone on the
scale .
-Driver intervention prompt : When ap
proaching rap idly, the arrow serves as an
early warning signal. If the d istance select
ed is exceeded or possibly not reached, the
arrow moves into the
red zone on the scale.
In certa in driving situations, you as the driv
er w ill have to take action
c::> page 124, Driv
er intervention prompt.
@Status
- The text ACC: Off appears in white letters
when adaptive cruise control is turned off.
- The text
ACC: Standby appears in white let
ters when the system is turned on but no
desired speed has been set.
- The text
ACC: override appears in white let
te rs when you exceed the desired speed by
acce lerat ing. - The text
DI
STANCE! appears in red letters
when the interva l to a vehicle traveling
ahead is too short and you have to slow your
veh icle additionally with the foot brake.
- The text messages
DISTANCE 1 to DIS
TANCE
4 appear in green letters to indicate
the t ime interval you have set and adapt ive
cruise control is in management mode.
- If the driving program "standard" is re
placed by "comfort" or "dynam ic" using the
MMI , the above text message is supple
mented by an appropriate prompt, e.g.
DIS
TANCE
1 -dyn .
System status indicator
Applies to vehicles : wi th adap tive c ruise contro l
The text messages and symbols shown in this
area of the display are not displayed perma
nently.
Fig. 137 System status indicator
Time intervals (such as.::::::, ____ .::::::,)
The different symbols for the time intervals
(distance) appear if you change the settings
c::>fig. 137.
Three white dots ... appear if a setting cannot
be made w ith the operating lever. The follow
ing are possible reasons
- If you pull the cont ro l lever towards you to
resume speed but no requested speed was
set.
- If you push the lever up to increase (or down
to reduce) speed when no speed has been
set previously.
- If you push the lever up to increase (or down
to red uce) speed and this speed is outs ide
Ill>