You cannot shoot someone for simply breaking into your car.
That is unless you're in your car and they are trying to harm you while breaking into your car and then you could shoot the person to stop the threat.
However if the person is just simply breaking into your car and then you shoot them for breaking into your car and you're not in danger then you will be arrested and if the person dies you could be charged with murder.
It would be a very hard thing to prove in court that the shooting was Justified for someone breaking into your car.
However the state laws vary but if someone is breaking into your car you may load a shotgun or point the gun at them but also call the police or just stay inside away from the person and then call police and then let the police deal with it.
The person breaking into your car could also have a gun and then turn around and shoot you.
Your life is worth more than your car or whatever is in it.
I would never even confront someone breaking into my car or even want to shoot them unless they were attacking me or trying to attack me while I was getting into the car or already in the car.