How much does car fuel consumption differ with and without air conditioning?

[LuciaFitz]

The difference is 20%. The car air conditioning accounts for about 20% of the engine's power, so using the air conditioning consumes a portion of the engine's power, leading to an increase in fuel consumption. The specific increase in fuel consumption depends on the car's displacement and speed. Details are as follows: 1. Impact on fuel consumption: For a car that typically consumes 10 liters per 100 kilometers, using the air conditioning can increase fuel consumption by about 2 liters. The effect of air conditioning on fuel consumption is very noticeable, while the impact of different fan speeds is relatively smaller. For example, assuming a car is used for urban commuting with an average fuel consumption of 10 liters per 100 kilometers. 2. Reasons for the increase: Taking an average daily driving distance of 25 kilometers: driving 25 kilometers consumes 2.5L of fuel = 16.1 yuan (6.44 yuan/liter); with air conditioning, fuel consumption is 3L = 19.32 yuan: an additional cost of 3.22 yuan. The car's engine essentially powers the air conditioning compressor, so when the cooling air conditioning is turned on, the pressure on the car's engine increases, requiring more gasoline to burn for power. This is why sometimes when the cooling air conditioning is turned on while driving, the car's power feels slightly weaker, due to the increased pressure on the engine.

[LilyMarie]

I've been driving for over a decade, and using AC does noticeably increase fuel consumption. One summer on the highway, my fuel consumption was 8L/100km without AC, but with AC it jumped to 9.5L, roughly a 20% increase. In stop-and-go traffic, it's even worse—the repeated cycling of the AC compressor can increase fuel consumption by up to 25%. Rolling down the windows? That works at low speeds, but once you hit 80 km/h, the increased wind resistance makes it even less efficient than using AC. Older cars are affected more—my decade-old SUV saw nearly a 30% increase in fuel consumption after the compressor aged. My advice? Don’t set the temperature too low; 24°C is the most economical.

[McAnderson]

That fuel consumption test last time was really interesting! Running the AC during city commutes burns 15% more fuel than not using it, which translates to an extra 3 yuan per day on gas—almost 100 yuan per month. The vehicle model makes a big difference; my friend's small-displacement car noticeably loses power when the AC is on, and you can literally watch the fuel gauge drop. Hybrids fare better since the battery can compensate for some of the AC's power draw. Weather is also crucial—after being scorched by the sun, the car interior gets extremely hot, and the AC working overtime causes the biggest fuel consumption spikes. Setting the temperature to 26°C with medium fan speed is the most fuel-efficient, using half as much fuel as the lowest temperature setting. I usually open the windows beforehand to cool down the interior before turning on the AC to reduce the load.

[DiDerek]

As someone who frequently drives long distances, I'm most concerned about AC fuel consumption. At constant highway speeds, using AC increases fuel consumption by around 10%, and it can reach 15% with frequent acceleration/deceleration. Why? The engine has to power the AC compressor! Smaller displacement engines bear heavier loads - I once drove a 1.5L car fully loaded with five people climbing hills with AC on, and fuel consumption instantly exceeded 11L/100km. The belt-driven compressor consumes at least 3-5 horsepower. Electric or hybrid vehicles with electric compressors perform much better, but for conventional vehicles, I recommend opening windows for ventilation when weather permits.

[LeStella]

Recent high-temperature tests revealed: Urban fuel consumption increases by 18% with AC on, and gets even worse in traffic jams. Does opening windows save fuel? Only valid below 40 km/h! But inhaling all the exhaust fumes isn't healthy either. Setting AC to 23°C saves 15% fuel compared to 18°C. Vehicle age matters significantly - my brother's old car has poor cooling and higher fuel consumption, but replacing the compressor immediately reduced fuel use by 5%. Actually, AC only adds 10%-20% fuel consumption, the key lies in driving habits: aggressive acceleration dramatically increases engine load, making the AC consume more energy.