88 octane unleaded without ethanol less expensive than 87 octane with ethanol?

May 7, 2004
Nokesville, VA
When E10 first came out, I had a car that consistently got 40+ mpg.

After E10, my gas mileage dropped exactly by the energy ratios of E10/E0!

I never saw 40 mpg again in that car running E10. E10 has less energy per gallon and you see it in the fuel economy!

The car was a 2004 Honda Civic HX.

I never noticed a difference. But where I live, we had MTBE in the gas instead of ethanol, till MTBE was replaced with ethanol because the oil companies didn't want to get sued over groundwater contamination. And a quick Google search indicates that 10% MTBE gas has about the same BTU content as 10% ethanol gas.
Jul 15, 2003
FWIW. I notice 0 difference in mileage with my 2019 F-150 5.0 or my 2006 2.0 Ford Focus. The Focus sees the same 50 mile drive to work with the only variables being weather. I usually got gas in my Focus at a Sams Club which was 87 octane E-10, but lately I have been going to a Kwik Trip which has 88 octane E-15 for the same price since the lines aren't long to fuel up. If anything I have gotten more consistant mileage with the Kwik Trip E-15, but that could be since the weather has warmed up and gotten better.