There is an excellent web site e-85 .com . It explains in great detail e85 and other alternative fuels. They also list all locations where it can be purchased by state. When I pheasent hunt in corn heavy midwest its a great buy. I run it in my Silverado with the TC loaded. I lose some maybe 15% in efficiency but in Ill, Mn, Iowa you can buy the stuff for as much as a $1 less.
Anything we can do to support our farmers and reduce foriegn oil imports is a plus for me. It burns cleaner as well. I think all gas sold around here has 10%.