What is the normal RPM for an automatic transmission car?

[VonMalachi]

For an automatic transmission car, maintaining a stable RPM between 1800~2000 is considered normal. Relevant information is as follows: 1. RPM: The engine speed affects the number of work cycles per unit time or the effective power output of the engine, meaning the effective power varies with different RPMs. Therefore, when specifying the effective power of an engine, the corresponding RPM must also be indicated. 2. Introduction: The effective power and its corresponding RPM specified on the engine's product label are referred to as the rated power and rated speed, respectively. The operating condition of the engine at the rated power and rated speed is called the rated condition. The rated power is not the maximum power the engine can produce; it is the maximum usable limit of effective power determined based on the engine's intended use.

[Cassidy]

As someone who has driven automatic transmission cars for over a decade, I think the normal RPM range is quite broad and mainly depends on what you're doing. When idling at a stop, engine RPM between 600 to 1000 is normal as long as the car remains stable without shaking. During acceleration for overtaking or climbing hills, the RPM may surge above 2000 or even 3000, and it's perfectly normal for the transmission to automatically shift gears to bring it down. When cruising at highway speeds of 120 km/h, the RPM typically stays around 2000 to 2500 for optimal fuel efficiency, so there's no need to worry too much. However, if the idle RPM drops below 600 and the car tends to stall, or if it exceeds 1000 with a humming noise, it's time for a check-up—it could be due to a dirty throttle body or sensor issues. Regular maintenance can help avoid these minor problems.

[McVincent]

From my daily experience driving an automatic transmission car in the city, I've found that an idle speed between 700 to 900 RPM is ideal. It's common for the RPM to jump up to 2500 during acceleration, but avoid keeping it at high RPMs above 3000 for extended periods as it wastes fuel and harms the engine. For highway cruising, maintaining RPM between 1500 to 2500 is best, where the engine sounds smooth. Abnormal readings like 500 RPM making cold starts difficult, or high idle speeds like 1100 RPM with noticeable shaking when the engine is warm, could indicate a clogged air filter or fuel injector issues. I recommend occasionally checking the tachometer as a habit, and if problems arise, get it checked promptly to ensure driving safety.

[DelMatthew]

For automatic transmission vehicles, engine speed varies with driving conditions. At idle, around 800 RPM is normal. When accelerating sharply, it may reach 3000 RPM before the transmission shifts up and stabilizes - don't worry about this. During cruising, 1500-2000 RPM is sufficiently high, and even up to 2500 RPM is acceptable. Only be concerned if idle speed fluctuates significantly below 600 RPM or exceeds 1000 RPM, as this may indicate spark plug aging - have it checked at a professional shop for simple peace of mind.

[MacTanner]

I think the normal engine speed is around 800 RPM at idle, within 3000 RPM during acceleration, and a stable cruising speed with the engine output at 2000 RPM is sufficient. Avoid letting the RPM surge sharply when the vehicle is under heavy load, such as climbing hills at over 3500 RPM, as this can accelerate wear and increase fuel consumption. If there are abnormalities, such as a temporarily high RPM of 1500 RPM during cold starts, it's normal if it doesn't persist. However, if the RPM doesn't decrease after a while, it may indicate a fault. Promptly check the engine oil and cooling system to maintain the vehicle properly.