Does a Car Consume Fuel When Idling with the Air Conditioning On?
2 Answers
Yes, a car consumes fuel when idling with the air conditioning on. Below are specific details about other factors that affect fuel consumption: 1. Engine Technology: Many people assume that larger-displacement vehicles consume more fuel, and this is indeed the case, which is why there is strong encouragement for the consumption of smaller-displacement vehicles. However, when there is a significant gap in engine technology, this pattern can easily be disrupted. For example, models equipped with Mazda's S-VT variable valve system, VIS variable intake manifold system, VTCS variable vortex control system, and VAD variable intake duct system in a 1.5L configuration can achieve a fuel consumption as low as 6.35L/100km, which is more fuel-efficient than many 1.0L models. Therefore, the technological level of the engine has a more significant impact on fuel consumption than displacement in some cases. 2. Transmission Type: The influence of the transmission on fuel consumption is evident, but the extent of this impact varies across different models. For instance, the Hyundai Elantra, a fuel-efficient family sedan, has a fuel consumption of 6.7L/100km for its 1.6L manual variant, while the Toyota Corolla manual variant consumes 7.3L/100km and the automatic variant 7.4L/100km, showing a smaller difference. This is because their transmission tuning prioritizes fuel economy, sacrificing some power by shifting earlier to achieve better fuel efficiency.
Having worked with cars for many years, I know quite a bit about the principles. When the car is stationary but the air conditioning is on, the engine is still running—it needs to drive the AC compressor. The compressor sucks in refrigerant and compresses it to cool, powered by the engine belt, so the engine must burn fuel to maintain its RPM. The AC fan is also electrically driven, and although the electricity comes from the generator, the engine powers the generator, indirectly consuming fuel. Simply put, idling with the AC on increases fuel consumption, roughly burning 0.5 to 1 liter per hour, which is even more wasteful than when driving. A common misconception is that the AC only uses battery power, but in reality, the car's AC system is designed to rely on the engine's power, with the battery serving only as a backup. Doing this long-term not only wastes fuel but also increases carbon buildup in the engine. My advice: if you're parked and waiting, running the AC for a few minutes is fine, but for longer periods, it's better to turn off the engine, open the windows, or use the fan-only mode to save fuel.
