Consumer Reports on Ethanol

Michael Giberson

Consumer Reports magazine put a 2007 Chevrolet Tahoe flexible-fuel vehicle running on E85 (an 85 percent ethanol/15 percent gasoline mix) through a battery of tests, and concludes it will cost consumers more than a gasoline burner. A chief limitation comes from ethanol’s lower energy content, which means that vehicles running on ethanol will have poorer fuel economy. According to the report, “in highway driving, gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 to 7 mpg.” They note that part of E85’s problem arises from use of an engine designed to work most efficiently with gasoline — an engine designed exclusively for ethanol would perform better. Not all results favored gasoline: Consumer Reports found a significant decrease in smog-building nitrongen oxide emissions when using E85.

Only a portion of Consumer Reports ethanol analysis is available online to non-subscribers, more appears to be available in the October 2006 print edition.


3 thoughts on “Consumer Reports on Ethanol

  1. Let’s see if they come around to design an ethanol-friendly combustion engine. I very much doubt it at the moment, because there is not enough incentive to do so. Even with a fuel efficient engine, ethanol (by default) has a lower energy yield than gasoline and therefore will always be more inefficient.

    It’s the same thing as with solar power, where the efficiency rating is an ideal optimum of 15% (coal power plant 48%) and it can’t be increased above this despite what the greens want to tell us.

  2. Let’s see if they come around to design an ethanol-friendly combustion engine. I very much doubt it at the moment, because there is not enough incentive to do so. Even with a fuel efficient engine, ethanol (by default) has a lower energy yield than gasoline and therefore will always be more inefficient.

    It’s the same thing as with solar power, where the efficiency rating is an ideal optimum of 15% (coal power plant 48%) and it can’t be increased above this despite what the greens want to tell us.

  3. Max:

    You’re statement about efficiency depends, of course, on the definition of efficiency. On a distance/volume measure, it will be lower, because of the lower energy density of ethanol, but the true measure of efficiency is the thermodynamic efficiency, that is, how much of the energy from combustion is converted into useful work. I’m not sure if ethanol is substantially better or worse than gasoline in this matter – if higher compression ratios can be used, then it is likely to be higher.

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