I am curious what reason he gave for impounding your car though. He could not just say, 'Hey...get out. I am taking this'.
I do have a friend who made some wisea$$ remarks to a police officer recently while being pulled over in his Lamborghini. As a consequence of smarting off the officer called the local police where he lives and said to pull him over and impound his car for anything he does....including his rear license plate not being mounted perfectly upright (which is impossible to do on a Diablo anyway). It all depends on the officer and the situation.
Personally, I have been pulled over TWICE on the highway for going 5 mph over, while being PASSED by cars going 10-15 mph faster than I was. Both times resulted in a ticket. Both times it was pretty obvious that the NSX was the reason I got pinched.