You should be able to 'shell' specific vehicles, just like in the original game. Allows you to bypass the vehicle limit without it getting stolen by the enemy.
In the original game, if some of your vehicles ran out of health, they become sort of totaled with a very low amount of health, but are still able to be fixed. Once that gets to full health, you returned that shell into working order (but with only 1 hp and had to be repaired once again), and if it reached 0 health, it would get permanently destroyed.