At about 3000 rpm, in any gear but most audile with windows open and at lower speeds, an intermittent rattle that sounds like it is tied to the induction/cam system comes and goes. Never happens when car is standing still regardless of RPMs. It is an additional rattle that is tied to the RPM. My mechanic has listened to it and is mystified. I told him I would ask the mighty mighty BMWCCA community for help. Thoughts? I just had him replace the cam position sensors and after that work this noise developed. Thanks folks!