How much does a roof top carrier affect gas mileage?

When just the roof rack was added, the car’s mileage dropped by almost 11 percent, or 5 mpg. But with the rack and rooftop carrier installed, the overall drop was 19 percent, a loss of 9 mpg. As we found when we tested roof- and hitch-mounted bike racks, the SUV’s mileage, on the other hand, showed less of a drop.

How much extra fuel does a roof box use?

More typically drivers are spending between 10 – 25\% more on fuel because of their roof box. This is because increasing the ‘frontal area’ of the vehicle destroys the aerodynamics. Even an empty roof rack can add up to 15\% to your fuel bill.

How much does a Thule roof rack affect MPG?

Beyond that, the two items tested with the least impact on gas mileage were the paddle board and Thule luggage carrier, both of which caused about a -19 percent decrease in fuel economy, or -5.5 mpg.

Do roof racks increase fuel consumption?

The roof rack increases fuel usage by 2 litres per 100kms on the highway and 1 L per 100kms in the city (with some highway driving).

Do crossbars reduce MPG?

Roof rails will not effect MPG, cross bars may to some degree and mostly is not only while traveling at a freeway speeds. If most of your driving is freeway and you’re worried about 2mpg then take the cross bars off when not in use.

Do roof bars affect fuel economy?

Use of roof racks requires vehicles to expend more energy due to aerodynamic drag. While there have been studies of their impact on individual vehicles—depending on the configuration, the fuel consumption penalty can be 0 to 25 percent on passenger cars—this is the first study to estimate impacts at the national level.

Do cargo boxes reduce mpg?

Adding any rooftop carrier, cargo box, or ski rack doesn’t come free. In fact, it significantly cuts your highway mileage all the time it’s installed, whether there’s weight up there or not.

Does a roof rack lower MPG?

There is no way an empty roof rack can affect gas mileage… Unfortunately, even an empty roof rack will affect mileage. Adding an empty roof rack to a vehicle can drop the gas mileage by about 7 percent! This means that adding an empty roof rack to a car that usually gets 35 mpg will drop the gas mileage to 32.5 mpg.