The air up there

The demand for nice-sounding fuel-economy numbers has led automakers to the wind tunnel, wherein a mysterious voice tells them to cut the aerodynamic drag or face the wrath of the marketplace. Then again, they can’t do a thing about the times when the marketplace messes up the drag coefficient on its own:

Automakers go to great lengths to make vehicles aerodynamic, adding grille shutters and painstakingly shaving off excess weight, but drivers are just blowing away the hard work with their roof racks, a new study reports (via CNET).

The effect of roof racks on fuel consumption was studied by researchers from Berkeley Lab and the National Renewable Energy Lab, who published their findings in the journal Energy Policy.

It turns out that showing off what an active lifestyle you have via a sporty roof rack (or just being too lazy to remove it after that one trip) accounts for nearly one percent of all annual domestic fuel consumption.

The study finds that 0.8 percent of light-duty vehicle fuel consumption in 2015 can be tied to the aerodynamic drag these racks asserted on the cars carrying them. That translates into 100 million gallons of gas burned needlessly every year.

In which case, you’ll perhaps be bewildered to hear that the single best fuel-economy reading I ever got from Dymphna, a 1975 Toyota Celica GT (2.2-liter SOHC four, 5-speed manual), was 29.1 mpg, achieved with a curio cabinet lashed to her roof. I am forced to conclude that the little Celica’s aerodynamics were so undistinguished that adding about a meter or so of wooden box actually improved them.

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