I once coasted (engine off), at midnight, down a long road, through a roundabout ('traffic circle'), then on. The police car hiding behind the car dealers then came after me with lights on etc
. I saw it from the corner of my eye before it lit up etc, and I reactivated the engine (gentle bumpstart in 5th) as my car was turning around the roundabout (so, taillight intensities were changing from their view anyway). It turns out it was a 'routine' stop, but most likely because I had an old car.
edit - of course, nothing was wrong with my car, it had tax / mot etc (which is what they were checking for)