What we did instead was use a 12-point 9/16 socket, but since the walls are too thick for the spark plug galley, we had to grind the socket down. BMW probably has a specific socket for this.
It’s not the prettiest job we’ve done, but it should do the trick.
When grinding it down, you have to make sure that the walls are thin enough to get all the way down onto the spark plug.
With the 9/16 12-point socket ground down, we can now get it onto the spark plugs.
Since the socket isn’t magnetic, we had to use a magnet to help pull it off.