Does an Automatic Transmission Car Have Idle Speed?

[VanPatrick]

An automatic transmission car does have idle speed. Below is relevant information about car idle speed: 1. The function of car idle speed: Idle speed is an operating condition of a car, referring to the engine running in neutral gear. The engine speed during idle is called idle speed. The idle speed can be adjusted by modifying the throttle opening size, etc. Idle speed means the engine is "producing power without doing work." When the engine is running, if the accelerator pedal is completely released, the engine is in idle condition. 2. Causes of unstable idle speed: Direct causes refer to mechanical parts being dirty, worn, or improperly installed, leading to changes in cylinder power output, resulting in uneven power distribution among cylinders and causing unstable engine idle speed; Indirect causes refer to abnormalities in the engine's electronic control system, causing poor combustion of the air-fuel mixture, making it difficult to balance power among cylinders, resulting in unstable engine idle speed.

[LaAdam]

I've been driving automatic transmission cars for over a decade, and this is quite common – when in D (Drive) gear, releasing the brake allows the car to creep forward slowly on its own, which is called idle-speed creeping. It's particularly handy during red lights or traffic jams, as the car inches forward without needing to press the accelerator. Manual transmission cars don’t have this feature; they only idle in N (Neutral) or when disengaged without moving. This design in automatic transmissions is mainly due to the torque converter and control system, which maintain the engine’s minimum RPM at low speeds to enable slow forward movement, enhancing driving convenience. This feature is especially practical for city driving, eliminating frequent gear shifts and reducing fatigue. Of course, if you don’t want the car to move, simply hold the brake. Always be cautious on slopes to prevent rolling when parked—developing good driving habits is key.

[VanNadia]

When it comes to idling in automatic transmission vehicles, I often use it myself, such as in parking lots or congested road sections. Releasing the foot brake allows the car to slowly move forward without pressing the accelerator. This phenomenon is unique to automatic transmissions, known as the creep function, where engine braking is reduced, and the wheels are propelled by the idle speed. In contrast, manual transmission vehicles do not move at idle unless the clutch is pressed and the brake is released, allowing for possible coasting. This design helps control speed, making it easier for beginners to handle, reducing accidents, and preventing engine stalling. Properly utilizing idle driving in daily commutes can enhance smoothness, but remember to regularly check the transmission fluid to ensure the system operates normally and prolongs the vehicle's lifespan.

[MakaylaAnn]

Automatic transmission vehicles do indeed experience idle movement. I've personally tested this by stopping in D gear, releasing the brake, and watching the car glide forward several meters. The reason lies in the transmission design: the torque converter generates slight torque output at low RPMs, working with the electronic control unit to maintain minimum engine speed and propel the vehicle forward. This is called the creep phenomenon, a unique characteristic of automatic transmissions, whereas manual transmissions remain stationary when idling in neutral. This feature enhances driving comfort, reduces starting vibrations, and provides safer starts especially on rainy days or slopes. Understanding this helps prevent misuse, such as avoiding frequent brake pressing in crowded intersections to prevent wear.

[OCollin]

I drive an automatic transmission car to and from work, and often encounter idle speed driving, especially when releasing the brake at traffic lights, the car moves forward slowly, which is effortless and convenient. This is a normal characteristic of automatic transmissions, stemming from the idle thrust set in the D gear, which manual transmissions cannot achieve. Discussing its advantages, it helps with smooth starts, making it suitable for beginners to practice, and allows movement at low fuel consumption, which somewhat aids in saving fuel, as it is more economical than frequent gear shifts in manual transmissions. However, attention should be paid to engine carbon buildup; prolonged idling can increase emission burdens. It is recommended to occasionally drive at high speeds to clear carbon deposits and maintain engine health.

[LaDeclan]

Thinking back to when I first learned to drive an automatic car, the instructor emphasized the importance of idle speed driving, which refers to holding the brake in D gear and then releasing it, allowing the car to move forward slowly on its own. This feature is very useful for controlling speed, especially when driving in narrow lanes or maneuvering into parking spaces. The core reason lies in the transmission design, which maintains low idle torque output, enabling the vehicle to move without stalling. Compared to manual transmissions that only idle without moving, automatics offer superior safety and ease of use. Extending this to daily driving, developing the habit of anticipating traffic and utilizing idle speed to reduce sudden acceleration can prolong brake life and also ease driving stress.