If the Agent moved 0-2 spaces he does not have to declare a direction when the motion detector is used.
If the car is moved at all, the motion detector cannot be used this turn. Vice versa if the motion detector was used, the car cannot be moved this turn.
Hunters must start their turn in the car to use the motion detector. (Except for Puppet).
Blue Jay's Holo or the Stealth Field does not confuse the motion detector.