The test fuel fuel is an ethanol free, specific blend that is 93 AKI(CARB's is 91). No retail gas station pumps it. The higher octane makes a difference when a car's engine is designed for premium, but the manufacture labels the car for regular.
I've often shown the differences in MPG between E10 & E0 for my five low compression 87 octane gasoline engines are 8%, 8%, 7%-8%, 7%, & 5%, which is way over the energy difference of 2.5% to 3%. In addition to the energy difference between E0 & E10, inaccurately "designated" 87 octane E10, is comprised of 114 octane ethanol & average 84 octane gasoline. Of course, 87 octane E0 IS 87 octane. It becomes understandable why the real-world MPG differences between E10 & E0, is nowhere near the energy differences. The "new" inaccurately "designated" 88 octane E15 that the "ethanol in gasoline industry" is trying to push, is 15 percent, 114(?) octane ethanol, blended into 85 percent, 83.5(?) octane gasoline.
. With Hurricane Dorian moving NNW up the eastern seaboard of the U.S., it is good that 1400+ sources of E0 are available in N.Carolina & S.Carolina, giving consumers extra capability & range in a full tank of gasoline. The extra capability gives extra versatility for instant changes in planning, if for any reasons, Dorian changes from directional predictions. Also, in gasoline generators, E0 will give extra length of service, at such critical times. Yes, in dire times there is no reason to choose any gasoline other than E0 for its efficiency.
A major plus I love, as N. & S. Carolina (many other southern states, too) exploded their E0 availability, is the wide range of octanes (from 87 to 94) offered to the public. Numerous states also are winding up their E0 availability. However, many of those states only make one octane widely available. As most gasoline vehicle owners use only 87 octane E0, they would be stranded or revert to 87 octane E10, in states that only offer high octane E0.
From pure-gas.org, there are now two milestones, one already accomplished & another very very near: 1) pur-gas.org just published 15,000+ sources for ethanol-free gasoline(E0) in the U.S. & Canada. 2) New York state has one source less than 1000 & should shortly be the first state to offer 1000 sources for E0. At least a handful of states offer well over 900 sources for E0. People continue to increase, who are learning that E0 is better than gasoline, that has at least 10% diluting ethanol corruption added to our nation's fuel stocks. Presently, about 11,000 more grass-roots inspired sources are available for E0, vs. E85 sources, which languish despite major backing by the federal gov't & "ethanol in gasoline companies".