E10 is sold throughout the country, a lot of states require it. There is a good chance most of the gas you bought was E10.
Your mileage should drop with it, but it should be about a 2 mpg drop. This is the most balanced
article I found on it.
I don't think EFI vehicles would be different, but I thought the temperature effect was interesting.
Is it possible you were just romping on the throttle harder because, well, you just wanted to get out of Kansas ?
