Does the EPA use E10 Gasoline for Fuel Economy Testing?

Did you ever wonder what kind of gasoline that the EPA labs use when they test new cars to come up with the official gas mileage figures? I’ve been pondering this question for a while. I finally got off my duff and called the Oak Ridge National Laboratory to find out.

Here’s something you might not know.

When they test cars for their official fuel economy numbers – the numbers that go on the window stickers and on the EPA website – they don’t use E10 gasoline (i.e.: just about all the fuel we can buy on the street). They use something called “Certification Gasoline.” It’s E0. It contains no ethanol, whatsoever. None.

How can these be considered accurate tests when the federal government isn’t using the same fuel that we use. Granted that when the tests were devised, there was no ethanol in the gasoline, but that’s certainly not the case today.

Does ethanol effect gas mileage? Yes, it does … to a certain extent. With a ten percent (E10) blend, it might lower mileage by approximately three percent (when comparing the 30 percent drop in energy content at 100 percent it works out to three percent at a 10 percent blend).

How in Heaven’s name can they expect us to believe the numbers that they’re printing on the window stickers when they’re not using the same fuel to test that we are using out here on the street?

The real world fuel economy difference between E10 and E0 is one of the little things we’d like to test with our new web series, Ain’t Fuelin’, but the series must be funded first …

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3 thoughts on “Does the EPA use E10 Gasoline for Fuel Economy Testing?”

  1. 3% might be generous. I experience around 10% increase in my 2001 Saturn every time I find a station that doesn’t use E.

  2. @Brian – I will get to test this in a semi-controlled environment, eventually. There are lots of variables …

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