Where is the brake fluid resevoir on E60. Tha manual says it is under the microfilter cover. Removed borth covers and I don't see it. Do Ihave to remove more parts to get to the routine maintenance item?
If the realoem.com diagram for the vacuum booster for a 2004 530i is similar to your car, the fluid reservoir is on top of the master cylinder which is bolted to the vacuum booster. Engine-side, it should be in-line with the brake pedal probably 8" or so off the firewall and several inches or so below the bottom-side of the hood. Sounds like there must be some other cover(s) to pull, perhaps.