Why is coasting in neutral prohibited?
3 Answers
Coasting in neutral is prohibited because: Here's a brief explanation of the dangers of coasting downhill in neutral. 1. Coasting in neutral can easily cause engine stalling. When driving at high speeds, engine stalling is extremely dangerous, especially when going downhill. Due to gravity, the vehicle's speed will continue to increase. When the engine stalls, the vehicle's steering system will fail, and the braking system will become ineffective. 2. When coasting downhill in neutral, the vehicle's speed accumulates, but you still need to control it. This means you have to constantly apply the brakes, which not only wears out the brake pads but also causes the brakes to overheat and potentially fail. In severe cases, this can lead to the cracking or bursting of the brake disc (or brake drum). 3. If you frequently coast in neutral, the driven wheels will drive the axle, which in turn drives the transmission. However, the transmission's lubrication relies on the gears (splash lubrication). When coasting, the transmission gears are not rotating, but the secondary shaft is. This can cause the secondary shaft to seize or result in severe wear between the secondary shaft and the gear engagement components.
After driving for so many years, I've found that the primary reason for prohibiting coasting in neutral is safety. When you shift into neutral and let the car coast, engine braking doesn't work, and all deceleration relies solely on the braking system. Especially on downhill sections in mountainous areas, the car can accelerate uncontrollably, and continuous braking can easily cause the brake pads to overheat and warp. In severe cases, the brakes may fail—I once experienced the frightening sight of smoke coming from the brakes. It's even worse in rainy or snowy conditions, as the vehicle is more prone to losing control and skidding due to the lack of traction and stability control, increasing the risk of accidents. Additionally, modern traffic regulations in most places explicitly prohibit this practice, considering it dangerous driving behavior. Therefore, for the safety of yourself and others, it's best to always stay in gear and let the engine assist with deceleration.
As a cost-conscious car owner, I've tested multiple times and found that coasting in neutral often wastes fuel instead of saving it. Modern engines can cut off fuel supply completely when coasting in gear, while neutral requires idle fuel consumption to keep running. Every time I tried coasting to a red light during my commute, I noticed a slight increase in fuel consumption. More importantly, frequent shifting to neutral accelerates transmission wear, leading to higher maintenance costs in the long run. From both environmental and economic perspectives, it's neither eco-friendly nor cost-effective, and poses significant safety risks – such as losing engine braking which extends stopping distance. My advice is not to take this risk. Developing the habit of coasting in gear is both economical and safer, while protecting your vehicle's lifespan.
