The car may be stolen. Call the police and have them come out and check. Have the license plate number handy and the car description when you call. "Hello, I'd like to report what I think is a stolen car." If it hasn't moved in over the month, get rid of it before it becomes an eyesore and a blight on your neighborhood.
I'm starting to think this car may be abandoned, as it hasn't moved in well over a month.
It wouldn't be an issue at all if it weren't for the fact that car is parked diagonally, almost taking over the next spot over.