[toss1]

Ethanol contains only about 67% of the available energy of gasoline on a gallon-gallon basis [0]. So mixing ethanol gasoline into gasoline will result in a noticeable loss of mile-per-gallon efficiency.

Agree that both are effectively releasing CO2 from either deep in the earth or from the soil, so replacing them with solar power generation on the fields would be a net plus, and probably a greater energy density. We could also use the new-ish practice of installing vertical solar panels between tractor rows of crops, which doesn't reduce the solar yield too much and allows both 'crops' to yield something.

That said, returning a lot to natural ecosystem may be necessary to our survival.

[0] https://afdc.energy.gov/fuels/properties