Do you really save money by turning off the air conditioning in your car?

The comfort in the passenger compartment comes at the expense of higher fuel consumption. But giving it up does not automatically mean savings

Cars have many options without which it is impossible to imagine a modern car. The air conditioner, multimedia system with amplifier, speakers, powerful low beams, wipers, heated seats, windows, and mirrors, as well as the ventilation of the interior, requires energy, which means that they put an additional load on the generator, causing the engine to use more fuel. How much does this cost increase if all systems are activated, and how much can be saved if the driver and passengers suddenly decide not to use the comfort benefits?

How much gasoline does an air conditioner use?
Power for the vehicle’s onboard systems is derived through the operation of a generator that has a direct connection to the engine shaft. If there is not enough power, then the control unit “orders” the motor to increase speed. Fuel consumption is increasing. Excess energy goes to the battery and is returned to the vehicle’s power system when the engine is off or running in power-saving modes, such as when idling. It is not surprising that drivers do not want to waste fuel, and many of them, for this reason, do not use air conditioning and other options.

Research by the German automobile club ADAC shows that the Skoda Octavia’s air conditioner consumes an average of 0.43 liters of gasoline per hour. If you turn off the air conditioning system, you can save this fuel.

Suppose you travel on a long road for about 10 hours, then driving without air conditioning there could theoretically be 4.3 liters of saved fuel in the tank. At the expense of this, however, the driver and passengers will have to put up with the high temperature of the air in the compartment.

Often the driver opens the windows to cool the cabin with the oncoming wind currents. In this case, however, the car’s aerodynamics are disrupted, and turbulence is created in the side zones, which form areas of low pressure, which in turn interfere with the free flow of the flow. This in turn slows the car down. Then the consumption increases again and can minimize the savings achieved from the non-working air conditioner.

Driving with the windows open
The magazine “Za room” does its research on the aerodynamics of cars. A diesel Ford Focus with a 1.8 TDCi engine and a Lada Kalina with a 1.6-liter engine participated in the tests. The tests were divided into two stages, at speeds of 90 km/h and 120 km/h.

At a speed of 90 km / h when driving on a highway without air conditioning, the Lada consumes 5.5 l/100 km. If you open all windows, then consumption increases by 0.1 l/100 km. However, as the speed increases, the situation changes dramatically. If you accelerate to 120 km/h, then the aerodynamic drag increases and the negative role of turbulence affects the movement. Thus, at 110 km/h, open windows increase fuel consumption by 0.35 l/100 km, and at 120 km/h – by as much as 0.5 l.

With the diesel Ford Focus, the picture is identical. At a speed of 90 km/h without air conditioning and with closed windows it spends 3.8 liters per “hundred”, and with open windows, there is an increase in consumption by about 0.1 liters. At high speeds, the consumption increases to 5 liters, and if you open the windows at a speed of 120 km/h, then the gasoline consumption will increase by about 0.4-0.5 liters. At a speed of 130 km / h with open windows, gasoline consumption increases by 0.6-0.7 liters. And this is more than the air conditioner consumes.

In general, turning off the air conditioner to save gasoline is recommended only at low speeds, no more than 90 km / h, but even in this case, the effect of saving is not obvious.

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