0 to park a car illegally next to a car that is already parked at the side of the road
1 to leave your car in the street along the side of a car that is already parked, so that your car is blocking other cars
They double-park and pollute the atmosphere, and are full of tourists who get out on the wrong side.
I know of many instances where people double-park as a matter of habit in narrow streets, leaving just enough room for one car to pass.