Roof boxes offer practical storage space for long trips, especially for transporting ski equipment. But you have to pay attention to the load, speed and fuel consumption.
Roof boxes cannot hold just any load. The maximum load depends on the manufacturer’s specifications and the roof load of your vehicle. This ranges from 50 to 100 kilograms, and you can find exact information in your vehicle’s owner’s manual. The weight of the trunk itself and the weight of the carrier system must also be taken into account. Important: The trunk must be well secured and must not slip or fall out while driving.
Legally, there is no explicit speed rule for driving with a roof box. Legally, it is considered a “load” and the speed must be “reasonable.” Some manufacturers recommend a maximum speed that should be adhered to for liability reasons. In general, the ADAC advises not to drive faster than 130 km/h with a roof box. On the one hand, a vehicle with a body is more susceptible to wind, e.g., crosswinds when a truck is passing. On the other hand, fuel consumption increases even more significantly at a higher speed. Measurements by the German automobile club ADAC have shown that a car with a roof box at a speed of 130 km/h consumes on average about 18% or one liter more fuel per 100 kilometers. For this reason, the roof box should be removed quickly after the trip or ski season.
Another tip: Remember that the overall height of the vehicle is greater with a roof box. Entrances to underground garages, duplex parking spaces, etc. should perhaps be avoided.