Does the BMW REQUIRE premium gas regarding pre-ignition OR does it require it to achieve the HP rating? Germans are good at putting Premium required for max HP but many will run on regular and the HP drops down. I doubt, IMO, that the BMW has to have premium to run. My old VW Vanagon with the VR6 engine stated the same, that it needed high test gas. The service tech back then told me that was for max HP and run it on mid grade or worse if necessary. It ran fine on either.