Roof Rack Gas Mileage

The roof rack mpg experiment.

Roof rack gas mileage.

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. The empty roof rack had a nearly 2 percent impact on fuel economy which translates to a little more than three quarters of a gallon of gas. Drag coefficient increases by speed squared. So it varies depending on the vehicle on the rack and on the driving highway or city but it s at least five percent and probably a lot more.

Berkeley lab says that roof racks cause as much as a 25 percent loss in fuel economy and accounted for almost 1 percent of national consumption in 2015. Off the showroom floor the regal tourx gets 21 miles per gallon in the city and 29 mpg highway for a combined fuel economy of 24 mpg. Some drivers may see their gas mileage drop by as much as 20 percent depending on vehicle type and type of roof rack. Mileage went from 41 mpg at 65 mph to 40 mpg.

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. So if your car usually gets 30 mpg on the highway and you add a full roof rack your highway gas mileage will drop to 24 27 mpg. Let s say that you drive 15 000 miles per year gas is 2 50 gal and your gets 25 mpg.