A few different ideas

[Joeri]

If possible;

-- PlayerA shoots at a tuned car
-- Message on PlayerA's screen "Do not shoot at tuned cars, or you will get jailed"
-- If PlayerA destroys the tuned car PlayerA gets jailed.
-- Tuned cars still take damage so people can't disuse it.

Possible?

then people can use an pimped car to drivedy others, it would be abused I think