Roof racks and external cargo accessories significantly increase aerodynamic drag and reduce fuel efficiency. While these additions are useful for travel, leaving them installed on a vehicle during daily use creates unnecessary resistance and higher fuel consumption.
Tests conducted by Car and Driver on a Kia Carnival showed that removing factory crossbars improved fuel economy from 25 to 28 mpg, extending the highway range by 60 miles or 97 km. These findings highlight the direct impact of external hardware on vehicle performance.
Consumer Reports found that a Nissan Altima experienced an 11% reduction in fuel economy, equivalent to 5 mpg, when driving at 65 mph or 105 km/h with a roof rack. Adding a cargo box increased this efficiency loss to 19%, or 9 mpg.
While aerodynamic penalties are less severe for boxy off-road vehicles like the Jeep Wrangler or Mercedes G-Class, they remain significant for crossovers, hatchbacks, and minivans. Drivers of these vehicles face increased fuel costs due to the added drag.
