Hello, don't know if you figured this one out yet, but the Brake Fluid Expansion Tank looks to be located underneath the drivers side microfilter housing. You have to remove the cover which is right in front of the driver under the hood, then the microfilter, then the lower housing.
Send me a note to
[email protected], reference the BMW board, and I can send you technical instructions with step by step diagrams in pdf form.
I haven't actually done this procedure since I have had my car for two weeks and it is still under warranty, so I cannot validate that these intructions are 100% accurate. But they are from a tech manual.
Mark.
By the way, if you need details on the pad replacement let me know, I can generate pdf's of those also (let me know front/back, pad's and rotors or just one).