Especially during the holiday season, many people use car accessories that can greatly increase fuel consumption. The roof box, which provides additional storage space, also means that the vehicle consumes much more energy.

ADAC warns: the roof box is the “largest additional consumer of fuel”

As the ADAC (Allgemeiner Deutscher Automobilclub eV) explains, the corresponding organizations are the “largest additional fuel consumers.” This is because “even at a speed of 80 km/h (…) consumption has already increased by around 11 percent. [steigt]at 130 km/h even up to 2 liters per 100 kilometers.”

According to experts, the reason is very simple: the friction caused by the air resistance caused by a roof box consumes much more energy. For this reason, it is recommended to do it “only with a roof box”. [zu fahren]if it is essential.”

How air resistance increases fuel consumption

The influence that air resistance can have on fuel consumption is not only shown in this example. Bicycle parking, among other things, can generate higher costs because it alters the aerodynamics of the vehicle. Above all this, but also an incorrect speed, has a negative effect, especially on long journeys.

The following influences fuel consumption in detail:

1. speed effects : Air resistance increases with the square of the speed. This means that it increases exponentially at higher speeds, significantly increasing fuel consumption. For this reason, vehicles tend to consume more fuel on highways than in the city, where speeds are generally lower.
2. Vehicle design : The shape and surface of a vehicle can significantly influence air resistance. Aerodynamically optimized vehicles, which have a smoother, more aerodynamic shape, experience less drag and therefore consume less fuel.

With these tricks you can also do it without a roof box

If you want to remove your roof box but still need extra space for your luggage, there are a few tricks you can use. These help to make optimal use of the available storage space. But remember: although this makes the vehicle more aerodynamic, the extra weight results in higher fuel consumption. However, it should be lower than with the roof rack.

Tips for carrying more luggage in the car:

1. trunk organizer : These allow you to better structure the room and store more items in an orderly manner.
2. Fold down the rear seats : If your car allows it, fold down the rear seats to create a larger cargo area. This is particularly useful for longer articles.
3. Use of footwells : The footwells behind the front seats often offer unused space that can be ideal for extra bags or smaller pieces of luggage.
4. Double use of articles. : Consider whether some of the items you carry with you can serve as storage for smaller items. For example, small objects or documents can also be stored in empty containers or suitcases.
5. Using vacuum bags : Vacuum bags can be particularly useful for bulky but soft items, such as clothing and bedding, as they significantly reduce the volume of these items.

Sources: ADAC, own research.

This article was created using machine-assisted (AI) technology and was carefully reviewed by the editorial team before publication.

By Dana Neumann