How much does a roof box affect my car’s fuel consumption? 

If you’re considering adding extra storage to your vehicle with a roof box, one important factor to keep in mind is how it impacts your car’s fuel efficiency. Roof boxes, while convenient, can significantly affect the way your car interacts with the air – and that means your fuel consumption.

Increased air resistance with roof boxes 

Roof boxes are mounted on top of the vehicle, creating a large, high-profile surface that increases air resistance or drag. When driving, especially at higher speeds, your car has to push harder against the air currents, which forces the engine to work more.

Research shows that roof boxes increase your car’s aerodynamic drag by roughly 30 to 40%, depending on the size and shape of the box. This increased drag leads to higher fuel consumption – costing you more money at the pump and reducing your vehicle’s overall efficiency.

Why a backbox like IXTAbox is more fuel-friendly 

In contrast to roof boxes, a towbar mounted cargo box (backbox) such as IXTAbox has a much lower impact on aerodynamics. The drag increase from a backbox typically ranges between -5% and +15% and under certain conditions, it can actually reduce drag.

How? If the backbox is narrower than the width of your car and mounted correctly above the underbody, it helps smooth airflow behind the vehicle. This reduces the overall air resistance, which can lower your fuel consumption compared to driving without any box or with a bulky roof box.

IXTAbox: designed for aerodynamic efficiency 

IXTAbox is engineered with improved aerodynamics in mind. Its shape and mounting position minimize air resistance, allowing you to enjoy a more economical and smoother drive.

Even the best roof boxes on the market – including popular brands like Thule – significantly increase drag and fuel use. With IXTAbox, you avoid these problems while gaining versatile, easy-to-access storage.