I usually get 23 to 23.5 on over the road cross country jaunts. That includes the flats of the eastern US as well as the Rockies in Dakotas, Wyo, Colorado, etc. But only 16-17 around town.
My dealer recommends mid-range gas, but since we are now getting 10% ethanol in almost all locations, I've gone to the premium grades all the time.
Interestingly, the service writer at Colo Spgs BMW told me we lose 3% of engine power for every 1,000 feet of elevation above sea level. Which means that at Colo Spgs, which is at 6,000 feet, I'm nearly 20% down in power vs. here at home in NY. And when I go to the top of Pikes Peak, at 14,110 feet, all I've got is about half power! Amazing!
Anyway, the car still runs like a champ!
Good luck to all.
Zen
