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.
Roof box fuel efficiency.
Do ski racks and roof boxes hurt fuel efficiency.
6 0 l 100 km 39 mpg thus the cargo box on the roof increased fuel consumption by about 5 compared to the baseline.
5 9 l 100 km 40 mpg roof mounted thule xtender 739 ski carrier with skis.
Yes more than you think.
Their study was published recently in the.
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.
They found that in 2015 roof racks nationwide were responsible for 0 8 percent of light duty vehicle fuel consumption or 100 million gallons of gasoline.
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.
As the british magazine what car.