Roof Box

Does A Roof Box Affect MPG? Roof Box Fuel Consumption

fuel consumption roof box

Roof Box Fuel Consumption Myths are widely spread across the community, as roof boxes are widely used and important. They give us the extra storage we need and are often lightweight, simple to install, and long-lasting.

This article discusses the facts and myths regarding the roof box fuel consumption effect.

Briefly: Unfortunately Some of those myths are actually true and roof boxes will increase your fuel consumption, depending on your vehicle type and the roof box being used. But don’t worry there are specific ways to decrease that.

How Does Cargo Box Affect Gas Mileage?

Having a rooftop carrier mounted on your roof adds many factors that weren’t taken into account when the manufacturers designed and made your vehicle. Thus a roof box MPG loss is inevitable, here are some of those factors


When you install a roof box, your vehicle’s shape changes which means having it will affect the vehicle’s aerodynamics as a result, your fuel mileage will be a little lower.

Depending on the size and form of the box installed, you will raise the level of air resistance, which means you will consume more fuel. Therefore installing a rooftop carrier, even when empty will always increase fuel consumption.

Added Weight

Do roof boxes increase fuel consumption due to added weight ? As we mentioned earlier even having an empty rooftop carrier installed will have an impact on your fuel consumption due to air resistance, not just that it’s the added weight from the roof box itself.

Any added weight in the vehicle such as luggage inside the trunk or an extra person traveling with you will lead to an increase in fuel consumption.

aerodynamic roof box

How Much Does A Roof Box Affect MPG?

It is quite useful to have a cargo box mounted to your vehicle. But, if you’re wondering how much does a roof box affect fuel consumption, you’ve come to the correct place.

The Consumer Reports stated that driving only with a roof rack led to a mileage decrease of about 11%, however, with the roof rack and roof box fitted, the overall decrease was 19%.

How To Have The Most Fuel Efficient Roof Box?

Although most rooftop carriers increase your vehicle’s fuel consumption, there are still things you can do to get away with the most fuel efficient roof box possible, so there is still hope regarding that.

Drive Slower

The lower your driving speed, the lower the drag and the higher your total fuel efficiency, thus traveling slowly with a rooftop carrier is always advised.

Regardless of whether having a roof box mounted or not, most vehicles will achieve optimum fuel economy in the region of 50 to 60 mph. So another reason to drive in that range.

We always recommend driving slowly and carefully when having a roof box mounted, especially if you are driving on unfamiliar roads.

Buy A Lightweight Aerodynamic Roof Box

Be sure to choose the most aerodynamic lightweight design available to reduce the amount of excess drag it creates, and in return decrease the roof box fuel consumption impact.

Some high-end roof box manufacturers specialize in aerodynamic lightweight designs to help reduce the cargo box gas mileage effect, such as Thule for example.

Remove The Rooftop Carrier

Obviously removing the rooftop carrier will enhance your fuel economy, so we always recommend removing it when not in use.

If you leave your rooftop carrier mounted all the time, roof box fuel consumption impact might be the least of your problems as it might be subjected to theft. Additionally, you will be annoyed by the constant wind noise it makes on the road.

aerodynamic thule roof box


So do roof boxes increase fuel consumption? is it a myth or a fact? unfortunately, The fuel consumption of your vehicle will be increased when adding a roof box depending on its size, shape, and weight.

Nonetheless, picking the most aerodynamic lightweight fuel efficient roof box may make things a lot better. As well as following the manufacturer’s guidelines for installing and using roof boxes.

If you still debating whether a roof box is worth it or not, make sure to check our article.

Finally, We hope that our small article is simple, useful, and enjoyable. If so feel free to support us by sharing as it motivates us to produce more content.

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