For anyone that doesn't have the spark plus tool that comes with the tool set, you will probably know that this tool is about £40 (or $58) from the dealer! I found out (and ordered) that there is also an actual 11/16 socket that is specifically for the M3 (i.e. it has very narrow walls). I will pick it up tomorrow and try it! It cost me £13 ($19). Email me if you want the part number. I don't want to post it until I try it!