I recently traded in my 08 Mini S that I bought new and ran ethanol free in it quite often. And when I did I got 2-3 mpg better mileage. And it seems like it had a little more power as well. It has gotten hard to find and here is a website that lists all the stations in the US that carries it Ethanol-free gas stations in the U.S. and Canada I've only had my SX5 three weeks and have run a couple of tanks of it and it seems like I gained a couple mpgs. It's a bit more expensive but I think it burns cleaner.