For those of with small cars or who frequently carry a lot of gear, roof racks are a godsend. They also look sleek. But as anyone who’s had them before knows, they’re noisy when loaded and can destroy your fuel economy.
How bad is the hit to your wallet? When Consumer Reports tested how roof racks affected fuel economy in 2013, they noticed a 5 mpg drop at highway speeds from an empty rack. Adding a bike to the equation caused fuel consumption to jump by 35% compared to their baseline settings.
According to a new study by Yuche Chen and Alan Meier published in the most recent issue of Energy Policy, “roof racks are responsible for 0.8% of light-duty vehicle fuel consumption in 2015, corresponding to 100 million gallons of gasoline per year.”
They calculated these numbers by crowdsourcing real world data (including forums), watching national highway videos to estimate rack usage, and estimating total vehicle miles traveled.
Their conclusion is that Americans could potentially save hundreds each year by simply unbolting their roof rack until needed. They also suggest that further research into developing aerodynamically shaped bars could help drastically improve fuel economy.