Myth: 15% Ethanol Fuel Will Destroy My Engine

[Bill USA]

2. all the detroit car manufacterers make them, but... they make no effort to take advantage of

ethanol's higher octane. So you get worse mpg on E85 than on gasoline. However, with the lower price it may balance out.
The auto manufacturers could make their FFVs get better mpg on E85 with a little effort. HOnda sells two FFvs in Brazil only (plentiful supply of ethanol there) which get comparable mpg on any blend of ethanol (from 20% to 100%) as they do using gasoline.


Mileage (mpg) Using Ethanol Seen 20% Higher Than EPA Says - Bloomberg
http://www.democraticunderground.com/112754153

A tweak to an automobile’s engine software can improve by as much as 20 percent the estimated fuel efficiency when using gasoline with ethanol or methanol, according to a non-profit group pushing gasoline alternatives.

A Fuel Freedom Foundation study showed that setting the engine to run at an optimal setting for the higher octane in so-called alcohol fuels can cut the greenhouse gases emitted on average by 17 percent to 20 percent, making it better for the environment than estimated by independent analysts and the Environmental Protection Agency.

“Alcohol fuels are not getting a fair treatment,” Eyal Aronoff, a founder of the non-profit group and co-author of the study to be released soon, said in an interview. With the correct analysis, “the greenhouse-gas emissions look really, really appealing.”

Fuel Freedom is an independent non-profit based in Irvine, California, that doesn’t have financial ties to the ethanol industry. It advocates for policies to build a distribution system for alternatives to gasoline in order to cut drivers’ costs and spur economic growth.
(more)

link to the study: http://www.fuelfreedom.org/white-papers-temp