Just to answer the original question because after reading nine pages of arguing I didnt see it. Sunoco. http://www.sunoco.navisite.com/index.html

Now to put in my $.02. I've daily driven my stock 2000 Mazda 626 (i4) for 8 years. I have always calculated my gas mileage after every tank. I have always gotten 25mpg city/30mpg hwy. After E10's introduction I consistently got 21mpg city and 26mpg hwy. After getting annoyed with the decrease in mpg I sought out stations that sell non-blended gas. Some do and don't here and there but the only brand that I have found consistent is Sunoco. Guess what? After switching back to good old 87 octane my mpg went back to normal. To bad my pos 2000 Mazda designed for regular gas consumption performs so poorly with E10, who would have thought? /sarcasm. You see, I don't believe that E10 is the problem. I believe the problem is when there is more then 10%. As someone else pointed out from a test, they saw 40% Eth.?! Holy crap! No wonder my mileage went to shit on the blended tanks I ran. I am not here to argue, you can dispute my findings I don't care. All I know is I calculate my mileage after every tank and these are my personal findings. I could only imagine what would happen should I put a tank of E10 that is actually E40 or higher into my tuboed rotary that is only tuned for plain old 93. Wait you say, no no it is a higher octane rating so it is good. Well, I am not tuned for it, nor am I going to attempt to have my car tuned again for a fuel that proves to not even be consistent. You see, in road racing, or any racing for that matter consistency and reliability are key.

~James