I have a 2012 128i coupe. I've had this rear clunking noise over small bumps or manholes from the drivers rear side. Strangely, this happened right after I swapped to my winter tires and rims.
I emptied the trunk and the noise is still present. New rear shocks (Bilsteins) were installed by a Euro shop in August - they checked over everything last week and the rear end is tight.
I did a search and read some threads. I thought the issue was the sunroof cover (when open), but as of today the noise is present regardless of sunroof cover (although the clunk is more muted when closed).
Its driving me nuts.
What else could it be? Is there something loose in my headliner? How do I check that?