BMW M3 2001, Manual

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M3 Engine concept Rain sensor
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BMW M will continue to develop BMW
engines for the performance-oriented,
yet responsible driver. That is why value
is placed on an engine design that
guarantees maximum thrust over a
wide engine speed range.
This is done by using high-grade mate-
rials and components with optimized
details. The engine thereby produces
higher speeds than can be achieved
with conventional engines.
Associated with the proper transmis-
sion gear ratio and an especially perfor-
mance-oriented engine electronics
system, the torque opens up with this
so-called "high-speed aspirated
engine" extremely evenly throughout
the entire engine speed range from
1,000 to max. 8 ,000 rpm.
In actual usage, this means improved
acceleration and more spontaneous
response throughout the engine speed
range, thus affording more driving plea-
sure.
Depending on how wet the windshield
is, the rain sensor controls the opera-
tion of the windshield wipers.
Infrared light is carried along the
surface of the windshield in an optical
conductor in such a manner that it is
reflected completely when the wind-
shield is dry. The quantity of reflected
light is measured.
If there is moisture on the glass, the
amount of light reflected is reduced
since the infrared light at the surface of
the windshield can escape. The quan-
tity of reflected light is thus a means of
gauging the degree of wetness on the
windshield.