ACE’s Hybrid Electric Flex Fuel (HEFF) demonstration project was extended a few weeks beyond the original three-year term to reach a total of 40,000 miles running on flex fuel. In August 2021, a used 2019 Ford Fusion Hybrid became “HEFF” with the installation of an eflexfuel.com converter, allowing the car to use ethanol blends up to E85. In addition to proving a standard vehicle could safely run on higher blends of ethanol, the HEFF project tracked mileage, ethanol content, and prices of gas and flex fuel to measure real-world, on-road emissions and costs for a hybrid electric vehicle using lower carbon ethanol flex fuel.
Forty-thousand miles became a target after Car and Driver published their 40,000-mile road test of a 2019 Tesla Model 3 LR (long-range) in April of 2022. The test caught our attention because we devised the HEFF project after seeing electric vehicle (EV) tailpipe and upstream greenhouse gas (GHG) emissions estimated around 150 grams per mile (g/mi), while full-sized hybrids emitted around 250 g/mi using regular gas. We figured hybrid emissions could drop to EV levels if gas was replaced with E85, and the EV we compared to happened to be 2019’s best-selling EV — the 2019 Tesla Model 3 LR. The dumb luck of Car and Driver doing a 40,000-mile road test on that exact vehicle meant we would be unlucky and dumb to not extend our HEFF test to 40,000 miles for comparison.
We drove HEFF 40,007 miles on flex fuel averaging 71.4% ethanol, with zero maintenance issues (not at all the case with Car and Driver’s Tesla). The 1,518 gallons of E71 divided over those miles works out to just over 200 g/mi tailpipe CO2. Had we been able to consistently use E85, that number drops to 176 g/mi, E85 made with CARB-certified low-carbon intensity (CI) ethanol would be 112 g/mi, and E85 with low-CI ethanol and renewable naphtha instead of gas would drop HEFF’s tailpipe emissions 75 g/mi CO2. Those fuels are all sold today in California.
Those numbers are still mostly higher than the fueleconomy.gov estimate of 111 g/mi GHGs for a 2019 Tesla Model 3 LR with its 310-mile range using average U.S. electricity mix. The thing is, Car & Driver’s test reported full-charge range consistently 80 miles lower than the 310-mile “sticker” throughout their road test. At 230 miles per full charge, the Tesla U.S. average electric mix number goes up to nearly 150 g/mi, and in some markets with higher-CI electricity, Tesla’s emissions exceed 260 g/mi.
Demonstrating E85 — and E85 in a flex-fuel hybrid in particular — as readily available tools in the fight to reduce carbon pollution was the goal of the HEFF project. HEFF has shown that anyone truly interested in reducing carbon pollution should be interested in flex fuel hybrids. We found out a lot of other things we’ll be sharing on the HEFF page at ethanol.org.
Happy Holidays and Merry HEFFin Christmas!
