well lets think about it.
the car is moving away from the transmitter at warp 9.
the transmitter is not moving.
so the signal will not be affected by doppler shift from the transmitter.
the car does not transmit back to the fm radio station does it. so no effect then.
so FM reception is ok in a moving car. it is just transmission that is affected.
Now if the transmitter was on a car doing warp 9 away from the listener it would matter of course.
hope that helps you understand.
Geoff