Idaho has been selling E-10 for years and I have 269,000 miles on a 91 S10 with no problems. When we had stations selling MTBE blend fuels I noticed no difference in fuel economy as the stations here blended the E-10 to have the same octane as the regular gas.
I will say that when the military switched from diesel fuel to JP-8 in all of their vehicles we found that switching back and forth caused the fuel filters to break down in just 1 or 2 tanks of fuel. It taught me to look closely at what you need to do to a vehicle to safely switch from 1 fuel to another.
As for the cost of producing ethanol, corn is not a good raw material to use for it. Using switchgrass or sugarcane produces much more yield at a lower cost per gallon.
