With my Highlander the difference close to 10%. When loaded up and hitting the freeways in California I average about 26.5 MPG at 65 MPH, but in Nevada using non-ethanol I average 28.5. I'm dubious about the ecological benefits of ethanol to being with because of its production methods (no benefit at all, and with some production methods even worse), and due to its lower energy you end up consuming more gas to drive the same number of miles. IMO, ethanol only serves to grease the political machine.
