[awodol]

For the car case, usually police shoot their radar at your license plate since it's a flat reflective surface anyways.

[tempestn]

And at headlights otherwise. But if your car has popup headlights and no front plate, and you paint it vantablack, you'd probably be close to invisible to police LIDAR (laser) guns. I'm not sure what the reflectivity of this stuff in the radio spectrum is though.

[samstave]

Do the black and yellow California plates still possess reflective properties?