[litesong]

87 octane 100% gasoline component (E0) is 87 octane. duh!
Reported in many websites, inaccurate but "designated" 87 octane 10% ethanol blend (E10) has a gasoline component that is 84 octane. Because of great quantities of "ethanol in gasoline industry" propaganda & lobbying to artificially lower E10 prices, American drivers have accepted 84 octane component gasoline to be used (not efficiently burned) in their 87 octane gasoline engines. But, 87 octane E0, as burned properly in an 87 octane designed gasoline engine, has 8% to 5% better MPG than inaccurate, but "designated" 87 octane 10% ethanol blend, which has neither ethanol component or gasoline component that is 87 octane.
Now the "ethanol in gasoline industry" is pushing inaccurate, but "designated" 88 octane, 15% ethanol-blend (E15). Inaccurate, but "designated" 88 octane ethanol-blend E15 has a gasoline component with an octane of 83.5.
If the "ethanol in gasoline industry" can successfully market inaccurate, but "designated" 88 octane ethanol-blend E15, they will then push inaccurate, but "designated" 87 octane ethanol-blend E15, which has its gasoline component as 82.4 octane. In all cases, the ethanol blends have no fuel components that are 87 octane & all ethanol blends are inefficiently burned.
The magic & power of propaganda to get people to accept products in their lives which are not "efficient" is remarkable.