I have a 2011 MCS. After spending many hours trying to find a buzz that sounded like it was coming from the area around the rev counter, I finally found it - it was the black trim around the sunroof!

Your ears can really fool you when trying the locate the source of a rattle or buzz, especially trying to do it while you are driving. The sunroof trim was very noisy when I tapped it lightly with my fingers - the whole circumference, front and back.

Solution: remove the trim and stick thin felt tape or similar to the bottom of all the tabs. Open the sunroof to see how the trim is fitted. Start from the front, there are two clips in the middle of the trim (also at the back). Be careful not to break these. Slide the blind a little forward to get to the clips at the back. No tools are needed and the trim is easily removed. Make sure the trim is dust free and clean before you stick on the tape. Also do the rear trim. If you tap the trim afterwards with your fingers you will clearly hear the difference.

This is not a good design and I think the treatment should be done on all R56 sunroofs. My car is really quiet now !!