As Jim said, preventing simple theft during the daytime does not justify lethal force.
There's some argument/dissenting opinions on this, especially theft from a vehicle, due to vehicles being included in parts of the Castle doctrine laws included elsewhere, and obviously walking up to your home in the middle of the day, even unoccupied, to find someone inside it robbing you can be justified deadly force. But, In this instance, I agree with Jim.
Now, if, while the car was speeding off, it had veered towards you, that changes the situation, as a moving vehicle can be considered a 'deadly weapon'
(Moving vehicles kill, like, eleventy billion more people then guns do every year)
Remember to Aim high when shooting through a wind shield from the outside, and to aim Low when shooting through one from the inside. Smaller calibres are affected more then larger ones.
Don't listen to what the movies show, Car doors & windows do not stop bullets, not even 9mm.
Or, if the thief had reached for something consistent with the draw of a weapon, it could also have been justified. Hope they have cameras in the parking lot for this defence though.
