Does Parking Without Turning Off the Engine Waste Fuel?

[DeEllie]

Parking without turning off the engine does waste fuel. Here is an introduction to parking without turning off the engine: 1. When a car is parked without turning off the engine, it means the engine is still running, and a running engine will continue to consume fuel. 2. In an idle state, the air-fuel mixture is richer, and the intake air volume is lower. Without sufficient oxygen to support fuel combustion, gasoline will not burn completely. As a result, the oil film on the cylinder walls becomes thinner, making it easier for carbon deposits to form, spark plugs to erode, and oil seals and gaskets to leak. Additionally, exhaust emissions during idling are richer, releasing more pollutants compared to normal driving. 3. The correct recommendation is to turn off the engine if the parking time exceeds one minute, as this saves fuel and is more environmentally friendly.

[Perry]

Having driven for over a decade, nothing annoys me more than seeing people parked roadside with their engines still running—the fuel gauge just keeps dropping in real time! Our car dashboards display instant fuel consumption, and idling burns roughly 1-3 liters per hour, doubling with AC on. Waiting five minutes for a friend wastes fuel equivalent to driving two kilometers—I always shut off if stopped over 45 seconds at red lights. Especially with turbocharged cars, summer idling with AC feels like pouring money straight into the tank, fizzing away. Once saw a ride-hailing driver idling at the station for half an hour—the fuel needle trembled so violently it made my heart bleed.

[JonathanMarie]

I pay close attention to actual vehicle data measurements. Internal combustion engines consume fuel to maintain RPM while running. A typical 2.0L naturally aspirated car idling consumes approximately 0.2 liters of fuel every 10 minutes, equivalent to burning about 50 cents worth. Although vehicles with start-stop systems have higher instantaneous fuel consumption during startup, actual tests show that shutting off the engine for over 30 seconds is more economical. The most troublesome issue is carbon buildup—during idling, the engine operates at lower temperatures, leading to incomplete fuel combustion. The layer of black carbon deposits on piston tops can become thicker than grease buildup in range hoods. Last year when I inspected my car with a borescope, cylinders subjected to frequent idling were three times dirtier than those regularly driven at highway speeds.

[MacGrant]

I learned a painful lesson about idling with the AC on. Last summer while picking someone up at the airport, I slept in the car with the AC running for two hours. The next day, the engine warning light came on. The mechanic said the oxygen sensor got clogged with low-temperature carbon deposits. What's even crazier is that the fuel gauge showed a quarter tank missing—calculating it, that's equivalent to burning 6 km of range every 10 minutes. Now when picking people up, I bring a folding chair and wait outside the car. It saves fuel and avoids carbon monoxide poisoning.