Someone backed into my uncle's M car, damaging the spoiler and cracking the tail light. There appears to be no body damage; HOWEVER, the trunk leaks.. even after the tail light has been replaced.

Any ideas? I thought the tail light gasket might be the problem (Common issue on e30's) but I decided to ask for another opinion. Could the trunk lid need re-aligned? Or is there some unseen body damage?

If the tail light was cracked it may have bent the mounting area around the lamp enough to prevent a seal, or opened the seam where the rear body and 1/4 panel meet. Good luck.