There is also a corner cube array on the side-front turn signal indicators. These do not present much of a target unless the police target you from the side in which case the cosine factor in speed measurement will give them too low a speed to worry about. Next in strength are head lights, brake lights, turn signal indicators, and fog lights. Of these, headlights are highest, followed by turn signals and fog lights. The retroreflection mechanism is interesting.
Light enters one-half of the light and is returned from the other half.
I suspect that the light enters one half, hits the back reflector, is focused near the filament, expands to the other side back reflector, and is recollimated returning towards the original source. This phenomena happens over a moderately narrow range of angles directly in front of the car. Grills, forward facing chrome, and any rounded specular material are the next strongest targets. Look for a bright glint from any rounded surface which always presents one small region facing the source. Flat regions are almost always pointed away from the source and hence do not contribute to the return.