212 Driving and Driving Safety
Automatic brake differential (ABD)
The ABD system controls the front and rear axles
separately. If one wheel of an axle starts to spin,
it is braked so that the other wheel on the same
axle can be driven.
The ABD recognizes different driving states, and it
features control strategies adapted to these
states. In situations in which little propulsive power
is required, such as when the car moves off on a
level gravel surface, traction control already be-
comes active at low engine speeds. If great
propulsive power is required, e.g. when moving off
on an uphill slope or for rapid acceleration, the
ABD is adapted accordingly.
A special off-road program is used in Low Range
mode.
Traction control system (TCS)
The traction control system prevents the wheels
from spinning by adjusting the engine power,
thereby ensuring good lane-holding ability and a
stable driving behavior.
Porsche Stability Management (PSM)
PSM is an active control system for stabilization of
the vehicle during extreme driving maneuvers. It
operates together with the Porsche Traction
Management (PTM) system.
PSM makes use of both the ABD and TCS sys-
tems, as well as the known functions of the anti-
lock brake system (ABS) and engine drag torque
control system (MSR).
Warning!
In spite of the advantages of PSM, it is still the dri-
ver’s responsibility to adapt her/his driving style
and maneuvers in line with road and weather
conditions, as well as the traffic situation.
The increased safety that is provided should not in-
duce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PSM.
Risks of accident due to inappropriate speed
cannot be reduced by PSM.
Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
– The system compensates for undesired vehi-
cle reactions (Ferraria effect) when the driver
releases the accelerator pedal or brakes on
bends. This compensation functions up to the
maximum lateral acceleration.
– PSM actively stabilizes the vehicle as required
during dynamic driving maneuvers (e.g. rapid
steering movements, during lane changes or
on alternating bends).
– Improved braking stability on corners and on
different or varying road surfaces.
– Improved brake functioning and reduced stop-
ping distance in the event of emergency brak-
ing.
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