Roof Box Fuel Consumption

Roof boxes reduce mpg.

Roof box fuel consumption.

A roof box has in impact on both. Leaving engines aside for a moment two major elements affecting a car s economy are weight and aerodynamics. But no matter how aerodynamic it might look it also alters the flow of air around your carefully shaped wind tunnel tested. 5 6 l 100 km 42 mpg roof rack with thule dynamic 800 aerodynamic cargo box.

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. Their study was published recently in the. Normally car does 33 mpg down to about 30 just now service due. Last year on a run to paignton 900 round trip we got about 35mpg fully loaded roof box included.

Couldnt fit into any car parks with a height restriction or multi stories. 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. However with the roof box it was only capable of 32 5mpg 31 per cent less than its claimed economy via the government tests. The biggest problem we had was parking.

The gear with the most impact were the dual mountain bikes strapped to the roof which impacted the fuel economy by 31 percent or 9 mpg. A close second was the kayak with 28 percent or a. 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. 5 9 l 100 km 40 mpg roof mounted thule xtender 739 ski carrier with skis.

Adding a roof box means your car has to carve a bigger hole in the air which requires burning more fuel so your mpg will suffer. Adding any roof box increases frontal area of your vehicle of course. I would guess a roofbox adds around 5 to fuel consumption although there are many factors at play especially if you if you sloiw down to 60 65 you may then even see a reduction in fuel compsumption.