What is the idle speed of an automatic transmission car?
3 Answers
Automatic transmission idle speed is around 1200 to 1500 RPM when starting a cold engine; when the water temperature is normal, the idle speed usually maintains between 800 to 900 RPM. If driving in D gear without pressing the accelerator, the speed is approximately 5 to 10 km/h. The idle speed of a car may vary depending on different engines and models, but the idle range is generally similar, normally between 800 to 900 RPM. When starting a cold engine, the car's idle speed will be higher because engine wear is more severe when working at low temperatures. When the engine computer detects that the engine temperature is relatively low, to avoid wear, the vehicle computer will increase the idle speed to allow the engine to reach operating temperature quickly and adjust to normal working conditions.
When driving an automatic transmission car, the idle speed typically ranges between 800 to 1000 RPM, depending on the specific model. My old car usually stabilizes around 850 RPM. The vehicle speed at idle is basically zero because you're parked and not pressing the accelerator. However, if you shift to D (Drive) gear and release the brake, the car will automatically creep forward slowly, usually at a speed of about 5 to 10 km/h, which is quite convenient in traffic jams as you don't need to constantly press the accelerator. Having driven cars of different brands, I've noticed that an excessively high idle speed may consume more fuel, while too low an idle speed can lead to stalling, affecting driving comfort. Regular maintenance should include cleaning the throttle body to prevent dirt buildup that could cause unstable idle speed. It's normal for the RPM to slightly increase in cold weather or when using the air conditioning in summer—this is part of the design. Remember not to confuse idle speed with vehicle speed: idle speed refers to the engine's rotation rhythm, while vehicle speed is the momentum of the wheels moving.
When I first learned to drive an automatic transmission car, I was also quite curious about the idle speed. In fact, idle speed refers to the engine's rotation speed when the vehicle is stationary, with a standard range of 800-1000 RPM. The vehicle speed is naturally zero at idle, unless you shift to drive (D) and release the brake pedal, at which point the car will creep forward slowly like a turtle, typically at 5-10 km/h, depending on the vehicle and road conditions. From my recent driving observations, if the idle RPM fluctuates up and down, it might indicate a faulty sensor or carbon buildup issues. Beginners should remember to regularly check the tachometer on the dashboard—normal idle sounds smooth, without excessive humming. Just clean the air filter during maintenance, and it should be fine.
