There is a drilling in the side of the plug in which you can put a size 3 Allen key or a Torx key T10 (usually found in the your BMW toolkit) in order to fit and remove it.
See tools
Also referred to as oil filler cap.
This brake pedal enlargement is nicely machined aluminium,...
These covers for the open holes of the rear engine mounting...
If the standard emblem with the chrome-plated R 12 lettering...