Lucky you can get gas without Ethanol. Not available here.
Only Sunoco has 91 by me, so I typically fill up with 93, preferably Shell.
Putting under 91 just does not make any sense. If you can't afford premium gas, you probably should not have purchased a BMW.
2014 535i xDrive Carbon Black/Mocha Nappa/Anthracite Trim/M Sport/Dynamic Handling/Sport auto transmission/Driver Assistance/Cold Weather/Luxury Seating/Premium