Cars and trucks are most efficient running at speeds well below the limit.

Infographic: On the Highway, Haste Still Makes Waste

Jan 14, 2021

by Jeffrey Winters

Does it pay to drive more slowly? The U.S. Department of Energy’s Oak Ridge National Laboratory runs a website, fueleconomy.gov, featuring a calculator that shows the energy use for vehicles at various speeds. To see how speed affects efficiency in the real world, data for a variety of popular vehicles was pulled from the site. Not surprisingly, popular pickup trucks like the Ford F-150 fare poorly in fuel economy while passenger sedans such as the Toyota Camry perform quite well. Indeed, even when driving a standard car hard, it still gets better mileage than a truck at its most efficient.

Across the board, however, vehicles running at 70 mph perform at about 80 percent of the efficiency that they reach at 55 mph. Haste really does make waste.

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