A joint study by researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) and the National Renewable Energy Laboratory have revealed something shocking:
Roof racks are bad for fuel economy.
Kidding aside, they've quantified/estimated the scale of the problem to the national level based on the prevalence of roof racks in freeway traffic audits.
Findings:
- in 2015, roof racks nationwide were responsible for 0.8 percent of light-duty vehicle fuel consumption, or 100 million gallons of gasoline
- fuel consumption penalty can be up to 25% on passenger cars
- people drive around with their roof racks empty eight times more than when loaded
- roof rack prevalance is estimated to increase by about 200% in the next 25 years (yay, "crossover" craze!)
From:
Roof Racks a Drag on Fuel Economy | Berkeley Lab
Full study:
Fuel consumption impacts of auto roof racks
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