Surprised at Gasahol Result

Maybe I didn't phrase or explain that well. Agree that from 40% to 95% the Chevron evaporates more easily. It was the other end I thought was interesting as it represents the conditions while the fuel is sitting in the gas tank or the carb bowls.

The light components in the Tier 2 EEE sample start evaporating at 74 F. 10% of that sample evaporated at 124 F.
In contrast it took 154 F to lose 10% of the Chevron sample to evaporation.

There seems to be some correlation between RVP and how easily the light end of the fuel evaporates.
RVP for the tested samples above
Chevron 6.7
Fuel A 7.74
Fuel L 7.6
Tier 2 EEE 9.07

Density for the tested samples above
Chevron ?
Fuel A .731
Fuel L .761
Tier 2 EEE .74

Based on the EPA page and Bimmer link you posted, it would seem the Benzene is one of the main components effecting the light end of the fuel and the RVP.