Cadillac 2015 ATS Owner's Manual page 218

ACC may operate differently in a
sharp bend. It may reduce the
vehicle speed if the bend is too
sharp.
When following a vehicle and
entering a bend, ACC may not
detect the vehicle ahead and
accelerate to the set speed. When
this happens the vehicle ahead
symbol will not appear.
ACC may detect a vehicle that is
not in your lane and apply the
brakes.
ACC may occasionally provide an
alert and/or braking that is
considered unnecessary. It could
respond to vehicles in different
lanes, signs, guardrails, and other
stationary objects when entering or
exiting a bend. This is normal
operation. The vehicle does not
need service.
Driving and Operating
Other Vehicle Lane Changes
ACC will not detect a vehicle ahead
until it is completely in the lane. The
brake may need to be manually
applied.
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