Reviewed By Anthony C (Scottsdale, AZ) Reviewed for a 2008 BMW 6-Series —12/25/2015 8:37 AM
I've always replaced the factory paper filters with a K&N filter for all my cars. They enable the engine to breath better, and although i didn't do a truly controlled scientific experiment on fuel economy/performance, my measurements always showed a better MPG. Also, for those concerned about it, I have never had any issues with dealerships and warranties, and the like. As long as you place the sticker on the airbox, they don't try to throw it out when the car is in for service.