The latest from Bob, MB mechanic:
...this problem according to a customer I just sent to Flagship with his ML500 reported back to me that the dealer has run out of loaners and Enterprize rental has no more rentals because they are out servicing cars with this problem!!!! According to what I have heard the problem is actually getting worse! For what its worth Audi is recomending Shell gas. For me this seems really suspicious. Look if they can't tell us what the substance is for sure how in the hell can they say with out equivocation that one brand is better than another??? I believe, that if this in fact turns out to be ethanol, as I have thought, than I believe I may be able to not only prove the theory but that I may be able to mitigate the ethanol one tank at a time.
So, I still don't know what's up. I'm in direct contact with this guy, and the AG will hear from me tomorrow.