Impound the car, strip it, and say "Sorry, we didn't find anything, here's your car in pieces."
A major problem is that often, especially on bikes, cops simply won't chase you if you're going fast enough. They just figure you're going to kill yourself anyway, and it's not worth risking their own life and the lives of others on the road (moreso than what you're already risking yourself) by chasing you.
The general consensus around here of all the cops I know seems to be sustained speeds in excess of 130 MPH. I guess they just can't hang.

__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"