Vehicle cooling: Experts recommend closing windows above 80 km/h

To balance cabin temperature and fuel efficiency, experts recommend a specific strategy based on driving speed. When driving at low speeds, such as in urban areas at 30 to 50 km/h, opening windows is the most efficient way to expel hot air without significantly impacting fuel consumption, as aerodynamic drag remains low.

However, once speeds exceed approximately 80 km/h, drivers should close the windows and use air conditioning instead. At higher speeds, open windows increase aerodynamic resistance, forcing the engine to work harder and increasing consumption. According to data from ADEME, using air conditioning in thermal vehicles can increase fuel consumption by 1% to 7%, while in cities, it can lead to a surconsumption of 0.2 to 0.5 L/100 km if the compressor runs continuously to cool a very hot interior.