That's where another earth strap is supposed to be. It connects to the bolt which should be 13mm head and the new earth strap will connect to a bracket on the exhaust close to where you found this one. You need to check by the passenger wheel up front as there should be another earth strap there. You definitely need both in my opinion as I even added a 3 ground. Your current condition could cause codes and issues.
A forum community dedicated to BMW owners and enthusiasts. Come join the discussion about Bimmerfest events, production numbers, programming, performance, modifications, classifieds, troubleshooting, maintenance, and more! Bringing the BMW community together.