Well, a 61% increase in fuel consumption simply by switching brands will not be accepted as plausible. If that were the case, automakers in the U.S. could meet their CAFE targets for the next many, many years to come just by using Shell premium during testing. Additionally, we don't have a lot of stories like yours out there, which, if the fuel were really that different, should be out there.
From a mathematically rigorous perspective, it's difficult to measure fuel consumption with an error bar of less than 10%, and the difference in fuel consumption between E-10 and E-0 typically falls within that noise. When I say you're going to get a rough ride over this one, it had better be mathematically rigorous, not to mention repeatable and verifiable by anyone.