Should You Shift to Neutral at Traffic Lights in an Automatic Transmission Car?
2 Answers
Shifting to neutral at traffic lights is the correct approach for automatic transmission cars, and using the handbrake in conjunction enhances safety. Engaging N (Neutral) gear with the handbrake applied can be more fuel-efficient, as the passive wheel in the torque converter of the transmission remains in an idling state, not adding extra load to the engine, which naturally reduces fuel consumption. More detailed information is as follows: 1. Waiting at traffic lights in D (Drive) gear with the foot brake pressed means the passive wheel in the torque converter between the engine and transmission is fixed, creating a counterforce on the driving wheel, thereby increasing the engine's load. This can be understood as hindering the engine's operation. Consequently, the engine's ECU increases fuel injection, leading to higher fuel consumption, which is why you can observe a high instantaneous fuel consumption when the car is stopped. 2. It is not recommended to wait at traffic lights in P (Park) gear because shifting from P to D can sometimes cause the car to reverse, affecting the vehicle behind and potentially leading to a rear-end collision, for which you may also bear some responsibility. 3. Some vehicles now come equipped with an 'autohold' function, which is an automatic handbrake. After activating this function with a button press, the vehicle automatically applies the brakes once stopped, eliminating the need to shift from reverse or drive gears, keeping the vehicle in a parked state. However, not shifting into neutral still poses certain safety risks, such as the vehicle lurching forward if the accelerator is mistakenly pressed, increasing the chance of a collision. Additionally, the auto start-stop function is also suitable for use at traffic lights, helping to save fuel to some extent, and the engine, when turned off, does not emit exhaust fumes into the car.
I usually drive an automatic transmission car and don't shift to neutral at red lights. Modern car designs are quite intelligent - just keeping it in D gear while braking is sufficient. This allows the engine to enter an efficient idle state, and the auto start-stop system will activate to reduce fuel consumption. Frequently switching to neutral actually wastes fuel because the engine idles without doing actual work. From an environmental perspective, fewer gear shifts benefit emission reduction. I've also noticed that braking in D gear illuminates the brake lights, alerting following vehicles. Unless the red light lasts over a minute, like at some long intersections, there's no need to bother. Overall, shifting to neutral offers few benefits while adding driving burden and affecting acceleration. I recommend developing the D gear habit - it's simple and practical.
