Sweet personal best honestabe.
I calculated your percent of difference (comparing your typical E10 fill-ups to E0) to be about 23.4%. Had to find something to occupy my time today - I'm home sick.
I realize that your experience is nowhere near strict ABA testing (temperature, tailwinds, good traffic flow etc. could have helped to boost mpg for that tank).
However, the large percent difference is hard to ignore. I can't help but wonder if some vehicles see greater losses from E10 than the 2-4% suggested by the EPA. 23.4% - even with so many other variables, it seems like a lot.
Somewhat related calculations (feel free to skip)
Of course, when your already up as high as ~50mpg, 23.4% doesn't mean as much in terms of fuel consumption as it does at, for example, 20mpg.
Over 1000 miles, an increase from 43.58 to 53.76mpg saves 3.83 gal. of fuel
Over the same distance, an increase from 20 to 24.68mpg (same percent increase) saves 9.48 gal.
The above is reminiscent of what I learned from
from Duke about MPG versus GPM as a measurement of FE.
But it makes me think: E10 seems to hurt drivers of larger vehicles more in terms of physical fuel consumption and of course cash.