Should You Shift to Neutral at Traffic Lights with an Automatic Transmission?

[MacOlive]

Automatic transmission cars can be shifted to neutral when waiting at traffic lights, and the handbrake can also be applied if the wait is prolonged. Here are the relevant details: 1. Duration for shifting to N (Neutral) at traffic lights: Placing the car in N for short periods while waiting at a red light is acceptable, but leaving it in N for extended periods can damage the car, especially the transmission. Keeping the car in D (Drive) while pressing the brake at a red light is akin to pressing both the accelerator and brake simultaneously in a manual transmission. This increases fuel consumption and, over time, puts prolonged stress on the torque converter, accelerating wear on components like the torque converter. 2. Avoid shifting to P (Park) at traffic lights: Shifting to P at a red light is not recommended because doing so without applying the handbrake can damage certain components; starting from P involves cumbersome steps; frequent shifting to P can cause gear grinding in the automatic transmission, damaging its bearings. The correct approach is to shift to N when braking; when the light turns green, shift to D and proceed.

[Brown]

I've asked many experienced mechanics about this issue. Actually, whether to shift to neutral at red lights for automatic transmissions depends on the situation. If the red light only lasts about ten seconds, there's no need to bother - just keep your foot on the brake in D gear, then release the brake when the light turns green. It's much more convenient. But for those long red lights lasting over a minute, I'd recommend shifting to N gear and applying the handbrake. This allows the transmission fluid to circulate properly and prevents overheating. Many new cars now come with auto start-stop systems - when you press the brake hard enough, the engine stops, so in this case whether you shift to neutral doesn't matter much. Just remember never to shift to P gear, because if you get rear-ended, the transmission could be completely destroyed. With over twenty years of driving experience, I believe keeping the brake pressed for short stops and shifting to neutral for longer waits is the most reasonable approach.

[Lamar]

As someone who frequently studies vehicle engineering, I tend to analyze from a mechanical perspective. When an automatic transmission is in Drive (D) with the brake pedal pressed, the torque converter is still operating but the power is cut off, which is equivalent to two rotating components continuously working against each other. Prolonged operation in this state can easily lead to overheating. Shifting to Neutral (N) disengages this strenuous condition, which is better for the transmission's longevity. However, modern transmissions have significantly improved cooling performance, so occasionally waiting at a red light in D gear is fine. If the auto start-stop system is activated, there's even less concern about overheating once the engine pauses. Nevertheless, for older models or vehicles with modified powertrains, shifting to N is more prudent. For daily driving, just handle it flexibly based on the duration of the red light—after all, frequent gear shifts may accelerate wear on the shifting mechanism.

[DelGenevieve]

To be honest, I usually drive in D gear and just step on the brake at red lights without bothering to shift. When my foot gets tired, I turn on the auto-hold function to let the system handle the braking. However, I switch to N gear when using the AC in summer, as the engine vibration feels noticeably reduced. If stuck in stop-and-go traffic, it's better not to touch the neutral gear—switching back and forth is too much hassle. Once, I forgot to turn off the auto start-stop, and the engine kept shutting off and restarting with every brake, which ended up using more fuel. My personal advice is to just leave it in gear for short stops like grabbing a drink—under 30 seconds, no need to fuss. For cars with modified exhausts, it's best to shift to N gear, otherwise, the exhaust drone in D gear while braking can be really annoying.

[DelLily]

From a cost perspective, keeping the car in D (Drive) mode while braking briefly is the most economical. Shifting to N (Neutral) each time requires passing through R (Reverse), which theoretically increases wear, but this is negligible. The main difference lies in fuel consumption: in N mode, the engine only maintains idle speed, while in D mode with the brake pressed, the engine works harder to counteract the transmission, consuming about 0.1 liters more per 100 kilometers. However, shifting to N mode when the air conditioning is on can reduce engine load. If the car is equipped with an automatic start-stop system, turning off the engine directly while stopped in D mode is actually the most fuel-efficient. Considering transmission repair costs ranging from thousands to tens of thousands, shifting to N mode during long red lights can indeed extend its lifespan. I've done the math: shifting to neutral for stops longer than 1 minute each time can save significant repair costs over ten years.

[Erik]

From a safety perspective, two key points must be emphasized. First, always engage the parking brake when shifting to Neutral (N), especially on slopes to prevent rolling. Second, never shift to Park (P) at red lights as a rear-end collision could severely damage the locking mechanism. Practical tests show that keeping the car in Drive (D) with brakes applied keeps the brake lights on, alerting following vehicles, whereas shifting to Neutral might lead to forgetting to brake, creating hazards. Vehicles with auto-hold function are most convenient as the system automatically applies brakes. For prolonged nighttime stops, I shift to Neutral to avoid dazzling following drivers with bright brake lights. In summary: short red lights - stay in Drive; long red lights - Neutral plus parking brake. This is the most balanced and safe approach.