Bloody european garages are pathetic, eh? I live in large town / small city quite near the centre and rent a garage and they are silly small!
The bit of cardboard on the right protects the door against the wall. Procedure is use key to drop window and then slide in like a pro. If the door windows had frames, no idea how you'd do it!
Euro cars have gotten bigger in recent years, a lot of these garages must be near useless for bigger modern cars with window frames.