[jphughan]

Wow, that sucks! I never bothered with my side bolsters the first year I had my M3, but the first time I tightened them up and went off for some spirited driving, I fell in love, and I was much faster and more confident at my next track weekend. This does sound like either a production error or a US advertising error. Ordinarily I'd think advertising error, but they clearly exist on non-US cars. On the other hand, production error seems unlikely too since the factory clearly has seats and button panels for the M multi-function seats sans bolsters. It's not like there's a hole in the button panel where the bolster adjusters should be, so it stands to reason that parts for this spec were intentionally developed for SOME purpose.

I don't see why airbags would be the culprit given that a) they exist on the M3, which has side airbags, and b) the bolsters exist on non-US M5s. Unless the side airbags are missing from non-US M5s??