Air conditioning and open windows: why there is no one answer for each route

Useful to know

Air conditioning uses energy, and open windows can increase air resistance. FuelEconomy.gov points out that the effect of windows is smaller at low speed and increases in highway traffic. [1]

External temperature, humidity and solar heating are important in air conditioning. Therefore, the general question "which one always spends less?" has no reliable answer without conditions. [1]

Practically, if you're comparing cost, write down the speed, the route, and the condition of the gym. A heavily heated car at the start of the journey is not an equal case of an already cooled saloon at the same setting.

The source offers a short airing to bring out the hot air before the air conditioner runs. [1] This is separate from a promise of accurate economy. Do not sacrifice visibility or necessary comfort because of an arbitrary number from a foreign test.