They always say "driving" is a privialage. So when it comes to all this racing BS, take away/suspend their DRIVERS LICENCE not their vehicle.
Now you just have a really expensive track car....because last I checked, you don't need a licence to drive on the track.
Sure speeding is wrong blah blah blah, but there is a big difference between speeding on a highway that was designed for faster speeds then the posted limit. And speeding in a 40 or 50km/h school or residential zone. They always seem to forget the fact that most of the cars they were driving can handle better at speed and stop faster then almost every other car on the road.
The average super car stop from 100km/h in a distance of around 30-35m. Your average car does it around 45m, some suvs are mid 60m's. Just throwing it out there.
http://www.youtube.com/watch?v=KGkKDaYd3Mo
old video, but kinda makes a point.