I only use 76 brand gas and 93 octane and live in the Southeast. It has 10% Ethanol or up to 10% but I think that only equates to maybe 3% less gas mileage. I've never owned a BMW that got the mileage from the EPA sticker, it always runs below it because who really drives the way cars are tested for EPA.
1995 325i,1996 328ci,1997 528i,1997 Z3 2.8,
2001 X5 3.0,2001 330i Conv,2002 M3 Conv,
2003 M3 Coupe,2004 M3 Coupe,2004 Z4 3.0,
2004 X3 3.0,2007 X3 3.0,2007 335i Conv.,
2013 X1 28 sdrive M Sport, 2014 M235 on order