I stopped using E10 when I started tracking my fuel efficiency. I noticed a significant performance improvement when I moved to regular unleaded. That's all that goes into my tank now.
I remember back in driver's ed, our teacher "encouraged" us to fill up with ethanol "because it's good for the farmers." Perhaps living in the nation's #1 corn producing state brainwashed us all. I don't believe in ethanol and I can't recommend it to anyone. E85 started off strong when it came out, but sales dropped off significantly since then. I think people are finally starting to understand the inefficiencies of ethanol.
E10 and e15 may be good for farmers, the agri lobby, and genetic seed companies.... But it is actually bad for the American consumer. Farmers are now growing more and more corn, and less and less wheat, alfalfa, etc. on great years the price per bushel of corn is stabilized due to the demand for ethanol, and on bad years the government shells out billions of dollars in crop insurance payments for the millions of acres of corn that shouldn't have been planted in the first place. Win win for all players involved... Except the tax payer who doesn't even want the damn ethanol in the first place and foots the bill. Using corn for fuel was a good idea after 9/11 and we needed a fast solution to imported oil, but now with hydro fracking shale oil reserves lets leave the corn for cows.... And pay less at the grocery store! You think mansanto will ever let that happen... Unlikely.