For those that use pure gasoline, just remember to use BMW Fuel System Cleaner in the tank every 6k miles to clean your injectors... Part of Shell and Shell like Gas stations that is good, is that they have chemicals (cleaners) that help your engine, that's basically the only good thing they have, so by using pure gas it would be helpful for you to use a Fuel Cleaner, like BMW's.
my 2 cents
