You most certainly can shoot someone for stealing a car. The problem is that prosecutors tend to frown on that behavior.
Unless the shooter can convince a skeptical cop and prosecutor, and a potentially more sympathetic jury, that he could have reasonably believed his life was in danger, it may not go well. As for a guy who can’t settle in advance on whether he shot the thief or a friend did, he’s not going to make a convincing case for self-defense, even if he has my full sympathy.
/johnny