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Old 07-27-2008, 07:06 PM   #26 (permalink)
Join Date: Jul 2008
Location: USA
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Sorry guys, I could not find that actual post from dcb, but here is his question: "Are you suggesting that the EPA method is an accurate way to predict MPG gains in the real world?"

My answer:

It is the only way I know. Certainly the Soceity of Automotive Engineers (SAE) would disregard "real world" testing without scientific methods. I am not suggesting that EPA tests necessarily reflect the actual mileage you will get. That will be influenced by altitude, vehicle condition, quality of gasoline, tire pressure, etc. But, it will scientifically demonstrate the relative benefits of any fuel economy product, which is the reason most product offerings don't do it. That's why I was interested in your test methodology. If your members do an ABA test themselves knowing which product has been installed, it is already a flawed test. If you wanted to make it more scientific, you could run a double blind test where the driver never knows what product is in the car and another person drives the car. The EPA drive cycle takes this subjectivity out of the test by forcing the driver to follow the computer. Of course it takes road conditions, traffic conditions and weather conditions out of the equation as well.

I once ran a "real world" fleet test with the U.S. government comparing products over 2 3 month test periods. One test period had 45% more idle time in it than the other. The government claimed that was "real world." I suppose if they simply parked their cars they would claim even better fuel economy. I know this sounds ridiculous, but it simply points out the subjectivity of "real world" testing. Today any company claiming fuel economy benefits and worth its salt must use recognized protocols or risk a visit from the FTC.

So, how do you guys do it?
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