In the cases of broken bolts...is the diff bushing still good? Are the dealers replacing them?
The subframe issue in the E46 was caused by worn subframe bushings. The bushing would excessively twist and load up the mounting point which would eventually fatigue the metal.
Maybe BMW improved the subframes and bushing design in the E9X but now created the problem with the diff bushings?
Maybe the heat from the exhaust (sans the heat shield) cause the diff bushings to fail from heat?
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red