Had a strange problem fixed this morning. Everytime I started the engine the fuel filler flap opened. As long as I closed it with the engine running, the central locking, when it activated automatically, kept it closed (and it didn't open when the Eco stop start started in traffic). Fixed at the dealers very quickly by fitting a new filler flap motor. I got the feeling that this wasn't the first time the dealer had seen this problem - they had a motor in stock! The flap opening looked like an air brake deploying. Car is a GLA 220cdi.