Not sure which 2005 BMW 5-Series Air Filters are right for you? We have over 3 customer reviews, with an average rating of 4.5, to help you find exactly what you're looking for. Freddy J from Bowie, MD said, "I purchased the squared K&N air filter on my wife daily driver and I thought I could tell instantly, so the first time she drove it she definitely noticed much improved throttle and gas results. My wife do not notice much about the car performance normally. KSo I say, You don't say!"