You are here

SUBSCRIBE to the Fact of the Week

While traveling for vacation, adding a cargo box on top of a vehicle can decrease fuel economy significantly compared to using a rear cargo tray. Testing was performed on two vehicles – a 2009 Toyota Corolla and a 2009 Ford Explorer with no cargo, with 100 lbs. of cargo in a cargo box on top, and with 100 lbs. of cargo on a tray at the rear of the vehicle. At 65 miles per hour (mph), the cargo box on top of the Toyota Corolla resulted in a decrease in fuel economy of 25%, but the cargo tray produced only a 1% decrease. The Ford Explorer’s fuel economy at 65 mph decreased by 10% with the cargo box on top, but by only 1% when using the cargo tray. The fuel economy decrease varies with the speed of the vehicle.

Toyota Corolla with Cargo Box on Top (left) and Cargo Tray on Rear (right)
Toyota Corolla with Cargo Box on Top (left) and Cargo Tray on Rear (right)

Fuel Economy by Speed for a Toyota Corolla and Ford Explorer with and without Cargo Storage

Graph showing fuel Economy by Speed for a 2009 Toyota Corolla with and without Cargo Storage. See dataset for more detailed information.
Graph showing fuel Economy by Speed for a 2009 Ford Explorer with and without Cargo Storage. See dataset for more detailed information.

Source: Thomas, J., Huff, S., and West, B., "Fuel Economy and ns Effects of Low Tire Pressure, Open Windows, Roof Top and Hitch-Mounted Cargo, and Trailer," SAE International Journal of Passenger Cars Mech. Syst. 7(2):2014, doi:10.4271/2014-01-1614.

Fact #981 Dataset

Return to 2017 Facts of the Week