Roof racks might be costing you significantly at the pump. In fact, a new study has estimated that the popular accessories are burning an additional 100 million gallons of fuel each year.
Furthermore, say the study’s authors, Yuche Chen and Alan Meier of the National Renewable Energy Laboratory and Berkeley Lab respectively, roof racks can reduce the fuel economy of a single vehicle by as much as 25 percent. In fact, these carriers of bikes and outdoor equipment may account for one percent of all the fuel consumed by light-duty vehicles in a single year.
Roof racks create aerodynamic drag, requiring the vehicle to expend more fuel to push through the air, especially at higher speeds. Often, roof racks are overlooked or not at all accounted for in fuel economy testing procedures because many of them are dealer add-ons or aftermarket accessories, installed after the vehicle has left the purview of automakers.
Compounding the issue is the popularity of crossovers and SUVs: the vehicles most likely to employ roof racks are the ones with lower fuel efficiency to begin with. Americans are also driving more than ever.
The authors recommend minimizing driving with empty roof racks, although even they admit this is unlikely to change. Instead, they believe that designing roof racks with fuel savings in mind will probably be the more likely route to burning less fossil fuels unnecessarily.