Does an Automatic Transmission Have Idle Speed?
3 Answers
An automatic transmission does have idle speed, which refers to the engine running without any load. Introduction to automatic transmission gears: 1. P gear is the parking gear, used when the vehicle is parked for an extended period; 2. R gear is the reverse gear, engaged when the vehicle needs to move backward; 3. N gear is the neutral gear, used when the vehicle is parked for a short time without turning off the engine; 4. D gear is the drive gear, when the gear lever is in D gear, the vehicle will automatically shift gears based on throttle opening and speed data; 5. S gear is the sport mode, making the vehicle drive more sporty; 6. M gear refers to the manual mode, when the gear lever is in M gear, gear shifting is done manually by the driver; 7. L gear is the low gear.
Automatic transmission cars do have idle speed. I've been driving for almost thirty years and noticed this when I switched from manual to automatic. Idle speed refers to the engine's rotation when the car is parked or in neutral. Normally, when you put the car in P (Park) and stop, the engine maintains a stable speed, usually around 600 to 800 RPM. Every time I stop at a red light or warm up the car, I can clearly feel the engine sound becoming quieter, but the engine doesn't shut off. Idle speed allows the car to start smoothly at any time, preventing it from jerking when you release the brake. As for the impact, prolonged idling does increase fuel consumption. I remember it being particularly noticeable when running the AC in summer, so I make it a habit to turn off the engine if I'm parked for more than a minute or two. Overall, the idle speed design in automatic transmissions is quite reasonable—it helps protect the lifespan of the transmission and engine—but drivers need to learn to control the duration.
As a car enthusiast, I must say automatic transmissions do have idle speed, which is a fundamental feature of almost all modern vehicles. Idle speed refers to the engine running at a standstill to maintain basic operation, typically controlled by the computer through fuel injection and ignition to keep RPM around 600. It's most noticeable when shifted to Neutral (N) or Park (P) - you'll see the tachometer stabilize within a certain range. Idle speed serves important purposes: ensuring the car is always ready to move, keeping air conditioning and lights operational, and preventing engine wear during cold starts. Nowadays, high-end vehicles even feature start-stop systems that automatically shut off the engine when stationary to save fuel, then quickly restore idle when the light turns green. From my research, too low idle may cause unstable vibrations, while excessive idle wastes fuel and increases emissions. Overall, automatic transmission idle speed is part of intelligent management - nothing to worry about, just drive normally.
