Sorry, just to clear this up. The power to stop any vehicle does indeed come from the uniform and NOT the car. You can be in an unmarked car in uniform and stop any car or be in a marked car, it doesnt matter. however, most people would stop if they see an unmarked vehicle with grille blues irrespective of what the officer inside was wearing. the only issue comes if the subject vehicle fails to stop in which case, plain clothes officers (in ANY vehicle) would have no power. i can say with with 10 years police experience and having encountered this issue personally.