[gone-ot]

...from the EPA website:

GASOLINE lower heating value: 116,090 BTU/gal
ETHANOL lower heating value: 76,330 BTU/gal

...thus, ethanol has only 2/3's the ENERGY content of typical gasoline, although it does have a much higher OCTANE (anti-knock) value:

GASOLINE: RON = 88-98, MON = 80-88.
ETHANOL: RON = 116, MON = 112

...unfortunately, OCTANE is only useful to high-compression engines and supercharging, while ENERGY content is indicative of power and fuel economy. That's why E85 has a higher OCTANE value of 105, but actually results in 2-10% loss in power and fuel economy. If the engine had variable compression ratio (CR), most of the power loss could be reclaimed using E85 (which can use higher CR), but not the fuel economy.

...so, "yes," non-alcohol gasoline will yield better milage.

...FYI: GASOHOL is basically E15 (15% ethanol+85% gasoline).