The local Kwik Trip has recently introduced an E15 gas with 88 octane. It's less expensive than Regular so I figured I'd give it a try in my Mini Cooper (2012 Hardtop Base). I'm in Wisconsin so all car gas is already E10 where I live. The car seems to run great on this fuel, and my mileage actually seems to be better. No pinging or other unhappy sounds. Is there any reason to stay away from E15 in a 2012 base Mini? My wife drives a 2016 Nissan Juke and her owners manual specifically says NOT to use E15 in her car. Thoughts?