For the record I have a very consistent commute and run 87 octane. I tried several triple-tank runs on Ethanol Free compared with my usual Top Tier Chevron and I got nothing out of it.
Chemically speaking, Ethanol has 93,000 BTU/gal and Gasoline is 126,000 BTU/gal (I'm going off memory so I may be off a few BTU). This means that energy-wise, a 10 gallon tank of E10 = 1,227,000 BTU. A full 10 gallons of ethanol-free would be = 1,260,000
According to my math, E10 has 97.3% of the energy of ethanol-free gasoline. This isn't a huge amount, but it should mean that if you normally get 25mpg, running ethanol-free gas should yield 25.7mpg in the same condition. It's not a huge difference.
The funny thing was though, I saw exactly the same fuel economy with no statistical difference. The sad thing about it was the fuel cost was 6-10% higher.
Bad buy in my book. Stick with E10 Top Tier.