Excellent comments, thanks for sharing and also for the great links. I can't believe I was right about the date! (1980's)

While those issues seem to more of the past then the present, speaking to BMW techs lately, high alcohol content in fuel is the current problem. One dealer told me of M3 / M5 owners in particular complaining of huge power losses that they couldn't explain or understand. After lots of diagnosis, it turned out their fuel alcohol content was enormous. The dealer would drain all the fuel and refill the car with specialty fuel they have in tanks and problem was solved. I believe BMW has a SIB on this as well.

In the end I think it basically depends on how one wants to run their car. I know people who change oil every 25,000 miles, never changed coolant, brake fluid, etc. put in the cheapest gas they can find, and have yet to experience any consequences. Personally, without going too overboard, I think that a precision instrument should be maintained accordingly. Thus I use the best gas I can find, only Shell or Chevron and always Super unleaded, and I always add BMW gas additive every 3,000-5,000 miles.
YMMV.