Why is coasting in neutral gear not recommended?
4 Answers
Coasting in neutral gear is not recommended because it can be dangerous and may generate excessive heat in the transmission, potentially causing damage. Whether it's a manual or automatic transmission, when coasting in neutral, the gears inside the transmission rotate at high speeds, instantly generating significant heat. Additionally, lubrication issues may occur during neutral coasting, making this practice harmful to the transmission. Neutral coasting refers to the driving technique where the driver shifts the gear lever to the neutral position while the vehicle is in motion, disengaging the clutch between the engine and drive wheels, allowing the vehicle to move by inertia.
This needs to be addressed from a safety perspective. I used to coast in neutral while driving, thinking it saved fuel and made the ride smoother. But I nearly had an accident once when driving downhill in mountainous areas: during continuous turns while coasting, the brakes suddenly became weak. I later learned that in neutral, the car has no engine braking and relies solely on the brake pads. After continuous braking for five to six hundred meters, the entire brake disc turned red-hot. If an emergency occurs on the highway, being in gear and stepping on the gas allows for instant acceleration to avoid danger, whereas in neutral, the power connection is at least two seconds slower—enough time for three rear-end collisions. Nowadays, traffic regulations explicitly prohibit coasting in neutral downhill. A fine is a small matter, but it’s too late when an actual accident happens.
Coasting in neutral is a complete myth when it comes to saving fuel! Modern fuel-injected vehicles automatically cut off fuel supply when coasting in gear, only resuming when RPM drops below 1500. I once compared real-time driving computer data: on the same 50 km downhill stretch, coasting in gear showed 0 fuel consumption, while coasting in neutral actually burned idle fuel. Prolonged neutral coasting also abnormally lowers exhaust temperatures, causing severe carbon buildup in the catalytic converter - cleaning costs later would be three times more expensive than any fuel saved. It's worse for automatic transmissions - the gearbox oil pump loses power, leading to insufficient lubrication and direct dry friction of planetary gears.
From a mechanical perspective, coasting in neutral damages three major components: insufficient transmission oil pressure accelerates wear, overheating of the brake system leads to heat fade, and insufficient power steering pump pressure makes the steering wheel heavier. Especially for automatic transmission vehicles, coasting in neutral causes the torque converter fluid circulation to stagnate, allowing metal friction debris to mix into the oil circuit. The worst case I've seen was a car owner coasting in neutral for three years, leading to a major transmission overhaul at just 80,000 kilometers. Although manual transmissions are less affected, the clutch release bearing continuously idling also shortens its lifespan. If you truly want to enjoy coasting, the smart way is to coast in the highest gear with the gear engaged.
