Acura 2006 RL Owner's Manual page 245

Limitations
ACC does not work below 25 mph
(40 km/h). It cannot bring your
vehicle to a complete stop.
ACC will not sound a beeper or
display a message on the multi-
information display to warn you of
vehicles going slower than 13 mph
(20 km/h) or vehicles that are
parked. In these cases, it is up to
you to maintain a safe distance by
using the brake pedal.
ACC may not recognize
motorcycles or other small
vehicles ahead of your vehicle.
ACC may react to vehicles beside
you or even building beside you by
momentarily applying the brakes
or sounding a beeper under
conditions such as a sudden curve
or narrowing of the road, an
abrupt movement of the steering
wheel, or if you are in an unusual
position within your lane.
Adaptive Cruise Control (ACC)
241