Rear Solid Sub-Frame Mount?

[bigjae1976]

Originally Posted by JAJ

Apparently this problem was so serious on early E46 (non-M) cars that early cars were recalled in the UK to reinforce the mountings. There was a running change on the production line, and by the time the E46 came to the US and Canada, the problem was fixed. It wouldn't surprise me if the E9x M3 chassis is reinforced at the mountings. The E36 and E46 M3 chassis were reinforced from the factory, but not enough for racing or heavy track use.

There have been plenty of cases of non-modified E46s that never see track time that had the rear floor failure. Apparently, sometime during the coupe LCI update 03/03 production and later), BMW started filling the floor with some sort of foam which has reduced the frequency of failures but there still have been failures in 2004 models.
Not to mention those models are 5 years younger so only time will tell.