check me if I'm wrong Sandy, but the M6 appears to have 20" wheels vs. the 19s on the M5.
2014 650xi GC, Imola Red/Black. MsportEd, CWP, B&O, 20" wheels
2011 1M, Black loaded sans sat radio
incoming... 2017 M2 LBB 6sp w/exec, Sept Production