Research suggests certain ethanol blends provide better fuel economy than gasoline, despite biofuel's lower energy content

Surprising research findings released today show that mid-range ethanol blends - fuel mixtures with more ethanol than E10 but less than E85 - can in some cases provide better fuel economy than regular unleaded gasoline, even in standard, non-flex-fuel vehicles and despite the biofuel's lower energy content. The University of North Dakota Energy & Environmental Research Center (EERC) and the Minnesota Center for Automotive Research (MnCAR) conducted the tests, results of which are published in the report titled Optimal Ethanol Blend-Level Investigation [*.pdf].

Previous assumptions held that ethanol's lower energy content - around 30% lower than gasoline - directly correlates with lower fuel economy for drivers. Those assumptions were found to be incorrect. Instead, the new research suggests that there is an 'optimal blend level' of ethanol and gasoline - most likely E20 or E30 - at which cars will get better mileage than predicted based strictly on the fuel's per-gallon Btu content. The new study, cosponsored by the U.S. Department of Energy and the American Coalition for Ethanol (ACE), also found that mid-range ethanol blends reduce harmful tailpipe emissions.

This is a compelling argument for more research on the promise of higher ethanol blends in gasoline. There is strong evidence that the optimal ethanol-gasoline blend for standard, non-flex-fuel vehicles is greater than E10 and instead may be E20 or E30. We encourage the federal government to move swiftly to research the use of higher ethanol blends and make necessary approvals so that American motorists can have the cost-effective ethanol choices they deserve at the pump. - Brian Jennings, executive vice president of the American Coalition for Ethanol

The University of North Dakota Energy & Environmental Research Center (EERC) and the Minnesota Center for Automotive Research (MnCAR) conducted the research using four 2007 model vehicles: a Toyota Camry, a Ford Fusion, and two Chevrolet Impalas, one flex-fuel and one non-flex-fuel. Researchers used the Environmental Protection Agency's Highway Fuel Economy Test (HWFET) to examine a range of ethanol-gasoline blends from straight Tier 2 gasoline up to 85 percent ethanol. All of the vehicles got better mileage with ethanol blends than the ethanol's energy content would predict, and three out of four traveled farther on a mid-level ethanol blend than on unleaded gasoline (graph, click to enlarge):
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In addition to the favorable fuel economy findings, the research provides strong evidence that standard, non-flex-fuel vehicles can operate on ethanol blends beyond 10 percent. The three non-flex-fuel vehicles tested operated on levels as high as E65 before any engine fault codes were displayed.

Emissions results for the ethanol blends were also favorable for nitrogen oxides, carbon monoxide and non-methane organic gases, showing an especially significant reduction in CO2 emissions for each vehicle's "optimal" ethanol blend.

References:
University of North Dakota Energy & Environmental Research Center (EERC), Minnesota Center for Automotive Research (MnCAR), Optimal Ethanol Blend-Level Investigation [*.pdf], December 2007.

American Coalition for Ethanol: Groundbreaking study finds that certain ethanol blends can provide better fuel economy than gasoline - December 5, 2007.