Surprising MPG results for low blends of ethanol

One of the "knocks" on ethanol (pun intended) is that for all the performance and emissions improvement that it provides as an oxygenate for gasoline, the more that you blend in, the lower the miles per gallon you should expect. For the lay person, that means more frequent stops to the filling station - roughly one extra fill-up for every three the vehicle currently requires. Even at price parity the annoyance of increased stops may deter some from using E85 (which is 85% ethanol/15% gasoline).

While it may be true for high blends of ethanol a new study provides laboratory evidence that E20 and E30 blends actually improved MPG on the automobiles tested!

The University of North Dakota Energy & Environmental Research Center (EERC) and the Minnesota Center for Automotive Research (MnCAR) conducted vehicle fuel economy and emission testing on four 2007 model vehicles. The vehicles tested included a Chevrolet Impala flex-fuel and three non-flex-fuel vehicles: a Ford Fusion, a Toyota Camry, and a Chevrolet Impala.

Highway Fuel Economy Test (HWFET) testing on ethanol blend levels of E20 in the flex-fuel Chevrolet Impala, E30 in the non-flex-fuel Ford Fusion and Toyota Camry, and E40 in the non-flex-fuel Chevrolet Impala resulted in measured miles-per-gallon fuel economy greater than predicted based on per-gallon fuel Btu content. It is notable that the non-flex-fuel vehicles obtained greater fuel economy at higher blends of ethanol than the unleaded gasoline. In the case of the flex-fuel Chevrolet Impala, the highway fuel economy was greater than calculated for all tested blends, with an especially high peak at E20.

While only three non-flex-fuel vehicles were tested in this study, there is a strong indication that non-flex-fuel vehicles operated on optimal ethanol blend levels, which are higher than the standard E10 blend, can obtain better fuel mileage than on gasoline. The Ford Fusion and Toyota Camry obtained a HWFET mileage on E30 of 1% greater than on Tier 2 gasoline; the flex-fuel Chevrolet Impala showed a HWFET mileage of 15% on E20 better than Tier 2 gasoline, as shown in Figure ES-1.

Exhaust emission values for nonmethane organic gases (NMOG), nitrogen oxides (NOx), and carbon monoxide (CO) obtained from both the FTP-75 and the HWFET driving cycles were at or below U.S. Environmental Protection Agency (EPA) Tier 2, light-duty vehicle, Bin 5 levels of 0.090, 0.07, and 4.2 grams/mile, respectively, for all vehicles tested, with one exception. The flex-fuel Chevrolet Impala exceeded the NMOG standard for the FTP-75 on E20 and Tier 2 gasoline.

It should be noted that it will take time to deploy E85 pumps in significant numbers throughout the U.S. During that time, the automobile manufacturers will be working not only on hybrid vehicles which improve MPG by sharing the load with plug-in and battery charges, but they will also be working on improving flex-fuel and ethanol combustion technology.

The automobile industry has had 100 years to fine tune their engines to work on cheap gasoline. Now that there is a mandate in the Energy Bill of 2007 to increase gasoline MPG significantly there will be significant research invested in improving performance on all kinds of fuels and configurations. Perhaps the relative energy content of the fuel will cause less concern to the driving public as the frequency of fuel fill-ups declines.

As far as emissions are concerned, that will be an area of focus for car manufacturers as well. They have innovated catalytic converters and carburetor designs in the past. There is no reason to expect less from them in the future as public demands turns to competitive environmental performance.

We will doubtless see many breakthroughs as thinking outside the fossil fuel paradigm box explodes.

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