Here is a twist..... you can get a GPS type system for a car. It will tell you where the car is, how fast it is going at the time, and where it is exactly. For example : Car is on I-5 Northbound at x exit and is going 95 miles per hour.
Hmmm, if that were my kid, he would lose his car. I value his life, and want to preserve it more than I care if he is upset that I have a device on his car and that I am violating his privacy. My kids do not have their own cars yet, but I have no problem putting that device on it, and letting them know. I will tell them that I will not police them, but from time to time I will pull a history of their driving. If they are caught recklessly speeding, then they get grounded, and lose the car.
Hopefully, just knowing that I might be watching will be enough to deter them from acting stupid.
This device will also allow you to disable the car, once it is turned off. Can you imagine it? Dad, I am going to library. And you find out that he is at Susies house. Hmm, that could be quite funny to disable it, and wait for that phone call.