Bob R. 6/11/2010The filter on the E-36 is to the left of where the passengers left foot would be. It's a little tricky getting out, but see the attached instructions blog site. You won't believe yhe amount of dirt that's clogging it and restricting the air flow to your A/C system. On mine, per the instructions, I crackedt the plastic case in two places and was able to snake it in quite easily after moving the wire harness connector that is in the way.
64 11 1 393 489 Interior Cabin Air Microfilter $27.95 at Bavauto.com.
The instructions are at this site: