Maybe you can take that evidence (i.e. pictures) and get a second opinion from an independent specialist that is trustworthy while also finding out if can be done cheaper.
Having said that, I had my differential nearly fall out of the rear and luckily was covered by warranty. I had been complaining about it for over a month, and they gave the all clear the first time around, so probably was more an "open and shut case" because they gave a clean bill of health after I brought up the potential issue. Also, I had no impact, aggressive driving/tracking/launches/mods and someone from BMW NA did have to look at it and approve it (that's standard operating procedure for this type of expensive issue). Despite it being covered by warranty (where one could argue they could have done the minimum to fix the problem), they replaced the differential, rear subframe, fuel tank and part of the exhaust, claiming there was damage to each of these components because of the differential nearly falling out. The "list" price on all this stuff ( I saw the work order) was over $13k.
You may also want to bring it up with BMW NA, or try to negotiate with the dealer if feel you can further argue the evidence is 100% conclusive that the bolt snap was impact related (2nd opinion also), given the prevalence of this issue. The mere threat of having the car towed to someone else may help your negotiating position (the dealer does include some margin on this type of stuff). Don't think anotherBMW dealer would yield better results, since the BMW NA reps that approve these typical service other dealers in the area. Perhaps a conversation with BMW NA and/or the BMW NA rep that looked at your car may yield more cooperation/better results. Best of luck.
Originally Posted by bvanderbilt
I am affected by this and joined this forum as a result of reading this thread.
I have a 2011 (100% stock, never modified) with 25k miles on it. I currently own three M3s -- two E46s and this E92. The E92 is my 'happy' car, I love the near-telepathic throttle response and drive it after particularly long days to unwind. The car (unlike my E46s) has never seen the track, has never been abused, and has never even had a bent 19" rim.
I took the car to the dealer (where I purchased the car) after hearing a faint clunking noise from the rear. A week later I am handed a "quote" for $6000. The differential bolt is broken off at the bushing. The dealer claims the sub-frame must be replaced. The dealer had an "FSE" come look at the car, who claims the car has had bottom impact damage.
I asked to see the damage myself and the damage is an inch long maybe 1/8" deep scratch to the passenger side fuel tank and some wear on a few of the differential fins, maybe from kissing a speed bump or road debris?
The dealer wants to replace the subframe, differential bushing & bolts, and fuel tank. They claim due to the "impact" it is not a warranty issue and I have to go through insurance.
I have a perfect driving record; going through insurance will be an at-fault accident which is unacceptable to me. I did not hit anything with the car and I have a hard time believing the fuel tank damage (a scratch, basically) is correlated to the differential, especially since the fuel tank sits higher than the exhaust and there is no exhaust damage whatsoever.
Dealership technician confirmed they found no hints of abuse whatsoever and could tell I took really good care of the car, saying it was "perfect" -- but claim they have never seen a broken differential bolt before and it must have been caused by impact. They also claim that it is BMW's decision and not theirs since the FSE wrote it up as accident damage.
Not sure how to proceed, advice appreciated. I think I could have the car towed to a reputable independent and have a new bushing and bolt installed at minimal cost, since this appears from this thread to be a relatively common issue, but I feel cheated by the dealer and their response.