How Much Do Roof Racks Affect Gas Mileage

The control test the tourx without roof rails.

How much do roof racks affect gas mileage.

40 mpg roof mounted thule xtender 739 ski carrier with skis. A five percent change in fuel economy is worth 75 each year or 375 in five years. Their study was published recently in the journal energy policy in a paper titled fuel consumption impacts of auto roof racks. 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.

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. If most of your driving is freeway and you re worried about 2mpg then take the cross bars off when not in use. Your fuel cost is ten cents mile or 1 500 year.

Generally adding a loaded roof rack to your car will lower your gas mileage by at least 10 percent. 42 mpg roof rack with thule dynamic 800 aerodynamic cargo box. Their study was published recently in the. 5 6 l 100 km approx.

39 mpg thus the cargo box on the roof increased fuel consumption by about 5 compared to the baseline. 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. Roof rails will not effect mpg cross bars may to some degree and mostly is not only while traveling at a freeway speeds. I ve put cross bars on two different odys with no measurable effect on mpg.

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. And since air resistance increases exponentially with speed the difference would have been even bigger at 70 mph many people drive at that speed. This editor many years ago in a move across the country to oregon from michigan found that the highway mileage of a four cylinder accord dropped from more than 40 mpg down to 32 mpg with a. Some drivers may see their gas mileage drop by as much as 20 percent depending on vehicle type and type of roof rack.

Some roof racks have cross members that can be unscrewed and stowed inside. 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. 6 0 l 100 km approx.