criminals can process all the info in their environment. An unmarked car, even if known, gives a slight advantage to the cops. But as you say a really conspicuous car, especially in a small area like a city for example, would be no more effective than a marked car.
But truly stealthly cars work. One of the WSP's found me last year. Where this cop was parked I would have had time to slow down if he was in a marked car, . That's probably why the state patrol here has so many unmarked cars now.
