That's odd, b/c ethanol actually decreases gas mileage by about 10%. Pure ethanol has an effective octane rating of about 105-106 octane, though, for those that want to run itNot recommended, however, if you are going to be using reg. gas, as well.
I dunno, to tell you the truth. The most I saw prior to my oil change was 320 miles/tank (16mpg). All I did was change the oil and make a decision to spend a lot more time following people instead of letting them follow me *lol*. Worked wonders. Don't get me wrong, I still get up on it every now and again, but I'm trying to be a better steward of my environment, whatever that means. I can't wait to see how much the mpg increase when I yank out the auto and put in the 5MT!