Does driving with windows open use more gas?
Many people often have the habit of opening car windows to get fresh air, so does opening windows while driving cause more gas consumption?
The Society of Automotive Engineers (SAE) conducted a test by driving cars in hot weather conditions. They used two different cars, one SUV with an 8.1-liter V8 engine and the other a sedan with a 4.6-liter V8 engine. The two cars were tested at the General Motors test track and also in the desert.
The results of the experiment surprised many people, SAE concluded that cars will consume less fuel when car users turn on the air conditioner and close the car doors.
Turning on the air conditioning in your car will consume a significant amount of fuel, however the amount of fuel consumed is still less than when you open the windows and drive, especially on the highway.
The reason is because when the car moves at high speed, the wind resistance is quite large, the more the windows are opened, the more the wind resistance increases. The car engine has to work harder to overcome that wind resistance and the car consumes more fuel.
However, some other studies have shown that cars will save more fuel if the windows are rolled down when driving at low speeds. Basically, that is the case when driving in urban areas. That means not driving on the highway, stopping at red lights often, turning at intersections often...
The reason is air resistance. When you drive at low speeds, there is less air resistance. Aerodynamics are not as big of an issue. Turning off things that use a lot of gas—like the air conditioning—will have a more direct impact on fuel economy.
Since every vehicle is different, there is no one-size-fits-all definition of “slow.” Studies generally show that cars use more fuel with the windows open when traveling at speeds of around 65 km/h. If you drive at speeds between 65 and 120 km/h, the car will consume more fuel with the windows open.
