New: The active cruise control

With the active cruise control, BMW introduces a support system which
relieves strain on the driver, especially whilst travelling on motorways
and other high-speed roads. This system is an extension of the well
proven cruise control. It does not only regulate speed, but - whenever
required by the traffic situation- it also regulates a constant distance
to the car in front in flowing motorway and highway traffic. The
active cruise control turns the classical cruise control into an
intelligent system. When the road is clear ahead, it operates in the
same way as the cruise control. The driver selects the desired speed
which he considers appropriate for the situation using the keys of the
multi-functional steering wheel; by pressing the "+" and
"-" buttons he can increase or reduce this by 10 km/h
gradations. The selected speed - 180 km/h as a maximum - is constantly
displayed by light-emitting diodes in the speedometer. The active
cruise control combines optimum and legal distance in practice If,
however, the car in front travels more slowly than the selected speed,
the system decelerates the car by reducing the throttle in such a way
that the distance to the car in front is increased so that it is
appropriate for the traffic situation. The driver's own car is then
travelling at the same speed as the vehicle in front. The distance,
calculated in metres is such that a firm time lapse in seconds is kept
between cars. It follows the rule of thumb of "half the speedometer
value", which is equivalent to a time lapse of approximately 1.8
seconds. In addition to this, the driver has the possibility to select
two further time settings, which however are definitely not within a
range which would not be permitted by law and therefore could be subject
to prosecution. Using the appropriate setting, the active cruise control
can also help the driver avoid illegal distances on which fines can be
imposed. As the system constantly determines the speed of the car in
front, it is able to react to changes of distance much earlier and much
more sensitively than a human being. The result is clearly improved
driving comfort with smoother acceleration and deceleration thus
ensuring a more relaxed way of driving, especially in a constant flow of
traffic Distance measurement by means of a radar system The most
essential element of the active cruise control is a radar sensor mounted
at the front of the vehicle which measures the distance, the lateral
position and the relative speed of the car in front. It has a measuring
range of up to approx. 120 m with a field of vision of +/-4°. If the
relative speed is zero - which is ideal for driving in such traffic
conditions - both cars are moving at an identical speed. As soon as the
system determines differences, it emits control signals which activate
the throttle or the brakes. The driver always remains responsible The
brake intervention is adjusted to a comfortable level for flowing
traffic conditions and is therefore limited to a certain rate of
dece-leration. Regardless of the situation, the driver is always
responsible for implementing the heavier braking manoeuvres. The active
cruise control is not a safety system in the sense of rear-end collision
prevention, or distance warning. To avoid misuse, there is just a small
telltale light in the instrument cluster which informs the driver about
the fact that the active cruise control has detected a car ahead
travelling in the same direction. Once again, drivers still remain fully
responsible for their actions and safety in every traffic situation.