How common is it for quality European car parts made for a certain car to simply not fit? I tried replacing the air filter in my BMW 535d today, but the Hengst filter I got from ECStuning would not fit. Although the old and new filters look identical visually, the filter gasket was ever so slightly bigger than the one on the Mahle that I was replacing. Result was the filter would not seat fully, which kept the cover from being able to close. I tried for over an hour without success; to make sure I wasn't doing something wrong, I reinstalled the old filter a couple of times and it fits and seats perfectly. I cleaned and vacuumed the old air filter as well as I could and reinstalled it until I can get a new filter, probably from the BMW dealer. In retrospect, I should have checked to see what brand of filter it had in it before ordering the Hengst. Frustrating! Hopefully ECS will refund or exchange the filter.