Beware of this tactic their unmarked police will use! You’re passing through town center Under the speed limit. The cop will let you pass his concealed position by ~100 yards, then race up behind you at speeds well over the posted limit. You instinctively speed up (unfortunately to a speed Over the limit) to avoid a rear-ending, and Bingo! He then turns the lights/siren on and relieves you of about $250 for you effort at avoiding an accident.