Does using the car air conditioner in recirculation mode or fresh air mode save more fuel?

[KhloeFitz]

Using the car air conditioner in recirculation mode saves more fuel. In recirculation mode, the air exchange channel between the inside and outside of the car is closed. When the fan is off, the air inside the car does not circulate. When the fan is on, the air drawn in comes from inside the car, forming an internal air circulation. The function of recirculation mode is to block polluted air, prevent external gases from entering the car, and ensure clean air inside the vehicle. To activate it, simply press the recirculation button inside the car. The car air conditioner is used to adjust and control the temperature, humidity, air cleanliness, and air flow inside the car cabin to an optimal state, providing passengers with a comfortable environment and reducing travel fatigue.

[DeEli]

I noticed when driving long distances that using recirculation mode saves more fuel, as it only circulates the air inside the car without requiring the AC compressor to process hot external air. This reduces engine load and naturally lowers fuel consumption. During summer heat, I close the windows and activate recirculation mode—the cooling is super fast with barely noticeable changes in the fuel gauge. Switching to fresh air mode introduces hot air and increases fuel usage. But don’t just focus on fuel savings—fresh air matters too. I usually switch to fresh air mode when outdoor air quality is good, but prioritize recirculation in smog or heatwaves. Regularly cleaning the AC filter also improves efficiency, preventing clogs that force the compressor to work harder and waste fuel. In short, flexible switching is key, and recirculation does save fuel in most scenarios.