How Much Do Roof Racks Affect Gas Mileage

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.

How much do roof racks affect gas mileage. 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. 42 mpg roof rack with thule dynamic 800 aerodynamic cargo box. 40 mpg roof mounted thule xtender 739 ski carrier with skis. 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.

A five percent change in fuel economy is worth 75 each year or 375 in five years. 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. If most of your driving is freeway and you re worried about 2mpg then take the cross bars off when not in use. Generally adding a loaded roof rack to your car will lower your gas mileage by at least 10 percent.

Your fuel cost is ten cents mile or 1 500 year. Drag coefficient increases by speed squared. 39 mpg thus the cargo box on the roof increased fuel consumption by about 5 compared to the baseline. 5 9 l 100 km approx.

Their study was published recently in the journal energy policy in a paper titled fuel consumption impacts of auto roof racks. The control test the tourx without roof rails. 6 0 l 100 km approx. 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. I ve put cross bars on two different odys with no measurable effect on mpg. 5 6 l 100 km approx. And since air resistance increases exponentially with speed the difference would have been even bigger at 70 mph many people drive at that speed.

Roof rails will not effect mpg cross bars may to some degree and mostly is not only while traveling at a freeway speeds. Their study was published recently in the. 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.