Can automatic transmission cars coast in neutral gear?
2 Answers
Automatic transmission cars should not coast in neutral gear. Generally, the gear shifting of automatic transmission cars is controlled by computer or automatically adjusts fuel supply or cutoff, which is different from manual transmission cars. Coasting in neutral gear does not achieve fuel-saving effects. Moreover, the design of automatic transmissions differs from manual transmissions; automatic transmission cars should not coast in neutral for extended periods as this can damage the transmission. The lubricating oil for automatic transmissions is supplied by the engine. When the engine is idling, the oil pressure output is relatively low, while the automatic transmission is still being driven by the rotating wheels and continues to operate. Low oil pressure results in insufficient lubrication, which can easily cause poor lubrication and severe wear on components such as hydraulic directional valves and planetary gears inside the automatic transmission. Additionally, this generates a large amount of heat, and excessive heat can lead to oil carbonization, forming sludge that blocks complex oil passages, resulting in insufficient oil supply and poor lubrication during normal operation.
I've been driving automatic transmission cars for over a decade, and I often hear people debating about coasting in neutral. To be honest, it's really not worth the risk. When you shift to neutral while the vehicle is moving, you first lose engine braking force. In an emergency situation where you need to accelerate to avoid danger, you simply won't have enough time, and the steering wheel will become heavier. I once tried it on a rainy day while going downhill on an elevated road section, and the braking distance noticeably increased - I almost rear-ended the car in front. Additionally, automatic transmissions rely on circulating transmission fluid for lubrication. Coasting in neutral prevents the planetary gear set from getting adequate lubrication, and doing this frequently can easily lead to transmission overheating or even failure. Nowadays, many vehicle models' ECUs automatically cut off fuel supply, making coasting in gear actually more fuel-efficient than coasting in neutral.
