Can an automatic transmission car be shifted into neutral while waiting at a red light?

[VanCassidy]

Automatic transmission cars can use P gear, D gear, or N gear when stopping at a red light. Below is a detailed introduction to gear selection when stopping an automatic transmission car: 1. Gear Introduction: (1) P gear: P gear is the parking gear and can be engaged directly without stepping on the brake or pulling the handbrake. However, engaging P gear requires passing through R gear, which can cause some impact on the transmission, although this impact is not very significant. Additionally, in the event of a rear-end collision while waiting at a red light, being in P gear can damage the transmission, so it is generally not recommended. (2) D gear: If the stop time is very short, this is acceptable, but it is best not to use D gear for prolonged stops. This is because with the gear lever in the driving position, automatic transmission cars usually have a slight tendency to move. Keeping the brake pressed for a long time forcibly stops this tendency, causing the transmission fluid temperature to rise and the fluid to degrade, especially when the air conditioner is running and the engine is idling at a higher speed, which is even more detrimental. (3) N gear: When the gear lever is in "N" gear, the power between the engine and the transmission is cut off, making it suitable for brief stops such as waiting at a red light. To prevent the car from rolling on a slope, it is recommended to step on the brake or pull the handbrake. 2. Precautions: N gear can also be used when starting the car or towing it. However, coasting in N gear is strictly prohibited. Some drivers shift to N gear to save fuel while driving at high speeds or going downhill, but this can easily damage the transmission. This is because the transmission output shaft rotates at a high speed while the engine is idling, leading to insufficient oil supply from the oil pump and poor lubrication conditions, which can cause the transmission to overheat and fail.

[LylaAnn]

I've been driving automatic transmission cars for ten years, and shifting to neutral at red lights is indeed a common choice. During long red lights, putting it in N gear can free up your right foot, eliminating the need to keep pressing the brake pedal, which significantly relaxes your leg muscles. Additionally, when in neutral, the torque converter and gear system disengage, reducing wear on internal transmission components. This is especially beneficial during summer traffic jams, as it helps prevent the transmission fluid from overheating. However, it's important to use the handbrake in conjunction, otherwise, the car may roll on slopes. Some newer models come with an automatic hold function, allowing you to stay in D gear for automatic braking, which can be more convenient than shifting to neutral. Overall, shifting to neutral is suitable for red lights lasting over 30 seconds, but for short red lights, it's better not to bother with gear changes.

[DelLena]

From a driving safety perspective, shifting to neutral requires cautious operation. I'm accustomed to shifting to neutral at long red lights, but I always firmly engage the handbrake to prevent rollaway accidents. When an automatic transmission vehicle remains in Drive (D) with the brake pedal depressed, there's constant pressure inside the transmission. Prolonged operation in this manner increases engine load, slightly raises fuel consumption, and gradually elevates transmission fluid temperature. Shifting to neutral eliminates these issues, which is particularly necessary during high-temperature traffic jams. However, you must quickly shift back to D when the light turns green and release the handbrake in advance to avoid being honked at by following vehicles. Many new cars now feature auto-hold functions that eliminate these operations, but shifting to neutral remains the safer choice for older models.

[ChloeDella]

Whether to shift to neutral at a red light with an automatic transmission depends on the specific situation. For brief traffic lights, there's no need to shift gears, as frequent switching can increase wear on the shifting mechanism. However, for long red lights lasting over two minutes, it's advisable to shift to neutral and engage the handbrake. This allows the transmission gears to completely disengage, avoiding continuous vibration in Drive mode, while the engine maintains only basic idle speed, which is more beneficial for the vehicle's lifespan. It's important to note that when starting again, first press the brake, shift to Drive, then release the handbrake and press the accelerator, ensuring the entire sequence is smooth and proficient. Different car models also vary; American cars may shake more in neutral, while Japanese cars tend to be smoother, so observing your own vehicle's characteristics is crucial.

[CeciliaAnn]

As an automotive technician, I recommend understanding the practical role of neutral gear. When an automatic transmission is in N (Neutral) gear, the input and output shafts of the transmission are completely disconnected, reducing the powertrain load by 20% compared to holding the brake in D (Drive) gear. This is particularly beneficial for older vehicles, as it prevents excessive wear on the clutch plates. However, each gear shift activates the shifting mechanism once, and frequent operation can actually reduce component lifespan. I suggest shifting to neutral only for red lights lasting over 60 seconds, and using the electronic parking brake for added safety. Modern vehicles equipped with auto start-stop systems eliminate this concern—transmission pressure drops to zero when the engine shuts off. In summary, using neutral gear wisely saves wear and enhances safety, but there’s no need to shift every time you stop.

[Wright]

From the perspective of energy saving and emission reduction, putting the car in neutral actually has little impact on fuel consumption. When waiting at a red light in D gear with the brake pedal pressed, the torque converter is in a semi-engaged state, which consumes about 5% more fuel. Shifting to neutral completely disengages the torque converter, eliminating this part of the loss. Especially in congested areas with frequent stops and starts, long-term accumulation can save a significant amount of fuel costs. Reducing unnecessary fuel consumption is also a contribution to the environment. Of course, shifting to neutral should be accompanied by using the handbrake to avoid rollaway accidents. Nowadays, more and more cars come with automatic start-stop functions, where the engine shuts off directly, making it irrelevant whether you shift to neutral or not. Considering all factors, shifting to neutral at long red lights is an economical and practical choice.