I have been experiencing a knocking sound when I select gears (most noticably first) on my 2000 318Ci and have put this down to diff mountings. However, I was speaking to a friend who had a 2000 328Ci just over a year ago who told me that he brought his to the main BMW dealer and they fixed it free of charge, as it is a major fault. Is this normal, or is there maybe more to his story?