I read a while ago that blends between 20E-45E could actually give better MPG but the amounts differed on different cars. I cannot find the original pdf it might be at home but a quick search came back with:
http://www.ethanol.org/pdf/contentmg...yStudy_001.pdf
http://www.ethanol.org/pdf/contentmg...se_12507-1.pdf
*This is bias due to the author of the study but I was thinking that the other document I had found was from a different organization but I could be wrong about that.