Is coasting in neutral or in gear more fuel-efficient for manual transmission?
2 Answers
For manual transmission, coasting in neutral at certain speeds is more fuel-efficient, but since there is no output from the engine and transmission driveshaft, it is advisable to shift gears while coasting to protect the transmission. The following is an introduction to manual transmission gears: 1. 1st gear: Used for normal starts or climbing very steep slopes. The speed is generally below 10 km/h when using this gear. 2. 2nd gear: Used as a transition gear for acceleration after starting, or for low-speed driving or climbing steep slopes. The speed is generally below 20 km/h. 3. 3rd gear: A forward gear, generally used at speeds between 20 km/h and 40 km/h, commonly used for city driving. 4. 4th gear: Can be used for speeds above 40 km/h up to 80 km/h. 5. 5th gear: Can be used for speeds above 60 km/h, typically used for high-speed driving.
I've been tinkering with car engines since my youth, especially manual transmission vehicles. When coasting in neutral, the engine idles and the fuel system continuously supplies a small amount of fuel to keep it running—consumption is minimal but constant. Coasting in gear is much smarter; modern electronic fuel injection systems can cut off fuel supply during deceleration, burning zero fuel while utilizing engine braking to recover energy. On downhill slopes or speed bumps, if the speed is sufficient, staying in gear actually saves more fuel because the vehicle's momentum drives the engine without fuel injection, whereas neutral coasting keeps burning idle fuel. This mechanism isn't as noticeable in older cars, but vehicles from the last two decades have been optimized—don't be misled by outdated notions. After testing with a fuel consumption monitor, I found coasting in gear saves 5-10% on average, especially in stop-and-go city driving. Adopting this habit protects both your wallet and the environment.
