It does create a wierd situation though, you can kill the guy in the car but can't do too much damage to the car itself. This guy for instance kept running me over with his sportscar. I just ended up joining a job but say I'd blow up his car as revenge, they should either consider it all bad sport behaviour (including his) or nothing at all. This really seems like taking half measures.
And also.. any sensible person would buy insurance before upgrading his car, so the loss is 0 in that case. All you have to do is pick it up at Mors once it gets destroyed, the only time you end up paying for it is when you caused it yourself. A 1k respray is cheap though.. those matte paintjobs can easily cost up to 15-20k