Roof Box Fuel Efficiency

Do ski racks and roof boxes hurt fuel efficiency.

Roof box fuel efficiency.

Adding a roof box means your car has to carve a bigger hole in the air which requires burning more fuel so your mpg will suffer. Adding any rooftop carrier cargo box or ski rack to your car significantly cuts your highway mileage all the time it. He found that compared to the baseline of no roof rack the empty rack reduced his mpg by 12 7 and the roof rack with a bicycle reduced it by a whooping 27 3. 5 9 l 100 km 40 mpg roof mounted thule xtender 739 ski carrier with skis.

5 6 l 100 km 42 mpg roof rack with thule dynamic 800 aerodynamic cargo box. Recently found adding properly fitted roof boxes and a modest amount of cargo to a couple of compact family models decreased their effective gas mileage by up to. Their study was published recently in the. It s impossible to give an exact figure because it depends on so many factors but britain s biggest roof box manufacturer thule states that your mpg is unlikely to decrease by more than 5.

6 0 l 100 km 39 mpg thus the cargo box on the roof increased fuel consumption by about 5 compared to the baseline. The roof rack mpg experiment he compared the gas mileage of his car at 54 7 mph 88 kph with 1 no roof racks 2 an empty roof rack and 3 a mountain bike on the roof rack.