Ethanol is the worst stuff you can put in your car. Here in StL we are forced to, all gas here in StL county is 90% gasoline, 10% ethanol.
For years I have wondered why I always get better mileage coming back from out of state. It's because out of state they sell 100% gas! And yes Missouri, Illinois, Kansas and Indiana are flat states, I'm not going uphill.
Gums up your engine and you get worse mileage (and performance). Remind me again Al Gore, how is running ethanol in my car helping the environment?