here is the study that a lot of people are refering to: http://www.ethanol.org/pdf/contentmg...inal_12507.pdf

30% seems to be a sweet spot for most vehicles tested. E85 gas is about 15% cheaper, so I figured I had nothing to lose by testing it myself. The only variable here is the human one as outside of a lab, 30% in the tank is hard to get accuratly. but if things are going to improve on the car, i doubt if it's not 30% exactly; ie 25-35%, it will matter much. I'm mixing in tank, so I know i'm a little off, but like i said, doubt it will alter testing outside of a lab much with all the other variable: weather, driving condition changes, etc.

How i mix: My first tank I know I've been using E10 for a few weeks, and know that's at the pump. So I added to the 13gl tank about 3gl of E85, and topped it off with regular. As soon as this tank is low (I'm going to wait until the gauge has 2 bars on it which is about 10gl low) I'll add ~2.25gl of E85, and top off with regular. This will maintain the ~30% mix taking account the 30% mix that's already in there.

-Fadi

1991 Mazda Miata to beat Corvettes at the track
1999 Dodge Ram to climb through rocks and brush
2004 Honda Civic Hybrid to make up for the other 2