I am a road-test editor by trade. Testing fuel-efficiency is a key part of my job. It seems odd that the EPA, NHTSA and CARB have teamed up on TAR, but that the DOE and USDA have been left out.
The Oak Ridge National Labs work on this topic is crucial. The world’s largest automobile manufacturers are all turning to highly-efficient downsized, down-speeded small displacement forced-induction engines. They produce more power with less weight.
Modern forced induction small-displacement engines LOVE high-octane low-carbon fuel. The most cost-effective way to achieve high-octane is with ethanol.
I have begun fuel efficiency testing with E15 fuel. My first E10 vs E15 test with a turbocharged 1.4-liter 2017 Hyundai Elantra Eco produced remarkable results: