Friday, December 28, 2007

Fuel Economy

After taking a detour into auto-mechanics in the last post, I think it's time to get back on track. This post will involve both evolving ethanol knowledge and its application in car engines. Before going any further, I want to add that this research is new and needs more verification before any of the results should be implemented. However, it is always good to keep track of the newest information.

The research, released in November of 2007, was conducted by the University of North Dakota and Minnesota State University and can be found at This study mirrors the call for more information on blending standards for cars in the United States. Currently, car makers will only honor their warranties on cars that fill up to E10 or a 10% ethanol blend in non-flex fuel capable cars. However, partly because of an anticipated excess of ethanol and because of a desire to blend ethanol in higher amounts to displace US imports of foreign oil there has been a call to look into the possibility of higher blends in non-flex fuel cars. The study looked at the the use of regular unleaded gasoline, E20, and E30 blends in four different cars. These cars were the 2007 models of the Toyota Camry, the Chevrolet Impala (flex fuel), the Chevrolet Impala (non-flex fuel), and the Ford Fusion. Results are displayed below.

As I mentioned before, the researchers would be the first ones to point out that the results are preliminary, but they are interesting. The above bar graph reveals the results of their tests showing that two models showed an increase of 1% in fuel economy for the E30 blend over conventional gasoline (the Camry and the Fusion), and the flex-fuel vehicle saw an amazing 15% increase in its E20 blend over conventional gasoline. Although unexpected, the researchers believe that some engines might have 'sweet spots' at which a certain blend might have the optimum combination of ethanol and gasoline to allow for a high mileage.

But what might be even more interesting is that all of the models of cars in all of the blends outperformed their calculated MPG based on their penalties for decreased energy densities. In other words, ethanol's energy density should result in a decrease in mileage by 2.7% for every 10 percent of ethanol blended into the gasoline. Below is an example from the sited study to reveal how the data bumped above the calculated energy density for the Toyota Camry.

As you can see above, the apparent 'sweet spot' in the Camry is around E30. Even though these tests need to be corroborated, they agree with similar results seen in 2005 in the study found at

While these studies show that E20 and E30 could be incorporated into non-flex fuel vehicles, a better potential benefit of this study is the realization that it may be possible to engineer a car engine to favor ethanol over gasoline, thereby relieving any potential MPG dip due to lower energy density. This would seem to parallel the finding in the previous post that a turbocharged engine built with ethanol in mind might be able to alleviate several of the potential negative aspects of ethanol.

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