My car was sitting running for an hour or so parked facing up a slight hill, so u wld expect the fuel gauge to be underreading slightly. But when i moved away it went up to 3/4 of a tank (i know this was wrong as it only had about £12 of petrol in it) then as i drove home it made its way up to completely full :? . I swiched the engine on and off a few times and eventually it made its way back to the correct reading. Anyone else had this rather confusing problem? Its a 2ltr 16v mk4.