The Complexity of Measuring Fuel Economy

A presidential mandate to improve truck fuel economy was accomplished with the stroke of a pen last month, but figuring out how to measure that improvement will be far more complicated. And if regulators aren’t careful, those measurement standards could actually end up producing trucks that consume more fuel in real-world operations than today’s vehicles, according to researchers and industry engineers.

Automobile manufacturers are held to corporate average fuel economy (CAFÉ) standards based on simple miles-per-gallon measures, but mpg “is not the appropriate measure for MHDVs (medium- and heavy-duty vehicles), since these vehicles are designed to carry loads in an efficient and timely manner,” according to the National Research Council, which created the report motivating the recent presidential mandate. “A partially loaded tractor-trailer would consume less fuel per mile than a fully loaded truck, but this would not be an accurate measure of the fuel efficiency of moving goods,” the group’s panel of researchers said.

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