I guess it depends on how the word is used. I think of obsession as strictly a personal thing, and almost everyone I know wants 0 or 1 car because it's difficult to get around without it. I'd consider that practical instead on excessive. Though I guess you could argue wanting your one car to be bigger or more expensive is excessive

Don't get me wrong, the culture definitely favors cars over pedestrians. I just don't think I'd use the word obsessive to represent that relationship

Edit: spelling