...picture of rear lisense plate? Can police cars calculate speed of oncoming motorbike (car in motion) and take picture of rear lisense plate of bike?
Of course they can get the speed of a moving vehicle, how else would they give speeding tickets? I don't know about taking pictures of the plate. Wouldn't surprise me.
BTW, cops don't have to be sitting in one place to get your speed; they can be moving too.