Why not go to a parking lot with a tape measure? Check a few and see how the car fits in each one. Pick the size that works.I have two lots that are 20' wide by 88' depth (or length). The house sits on one of those lots and the other one is open. They are right next to each other.
What I would like to know is how much of the free lot do I need to park two cars next to each other. Is 20' wide enough? How far in do I need to go?