If fuel consumption is a concern invest in a streamlined box which will cut through the air more efficiently.
How much do roof bars affect fuel consumption.
Their study was published recently in the journal energy policy in a paper titled fuel consumption impacts of auto roof racks.
It depends tremendously on who you ask and what vehicle is used.
Our experiment aired on television during season 2 of whichcar tv and involved three 100 kilometre road loops along melbourne s m1 freeway completed at the same 100km h average speed coming back in between each run to the same pump at the same petrol station to get as accurate a representation of fuel consumption as possible.
An empty rack has been reported to increase the cost of fuel over time from anywhere from 1 to 15 while a fully loaded roof rack will add 20 to 50 to your fuel bill.
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.
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.
Ie their was no difference in fuel consumption with either only that some makers of roof racks were noisy well having the windows open over 50mph is worse than having the air conditioning on.
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.
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.
Mileage went from 41 mpg at 65 mph to 40 mpg.
I ll justify these numbers below.
The control test the tourx without roof rails.
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.