Is coasting in neutral or coasting in gear more fuel-efficient?
3 Answers
Between coasting in neutral and coasting in gear, coasting in gear is more fuel-efficient. Coasting in neutral: This involves shifting into neutral and letting the car glide forward by inertia. It's important to note that coasting in neutral is only applicable to automatic transmissions; manual transmissions should never coast in neutral. When a manual transmission is in neutral while moving, the transmission is still operating, and the lack of lubrication can cause wear. Coasting in gear: The engine is between low-speed fuel cutoff and high-speed fuel cutoff. At this point, the onboard computer detects that the car is idling, but the speed is higher than the engine RPM, so the computer will stop the fuel supply to the engine. Precautions for using a car engine are as follows: 1. Avoid driving in neutral: The engine itself has a deceleration fuel cutoff function, and driving in neutral is not conducive to fuel economy. 2. Pay attention to observation when using the vehicle: If you find oil on the ground, determine whether there is an engine oil leak and communicate with the car dealership promptly to eliminate safety hazards. 3. Do not turn off the engine immediately after high-speed driving or climbing a hill: For cars equipped with turbochargers, let the engine idle for 10 minutes before shutting it off. Turbocharged cars accumulate carbon deposits several times faster than naturally aspirated cars. 4. If water is mixed into or absorbed by the brake fluid: Replace or carefully filter it promptly; otherwise, it may cause insufficient braking pressure, affecting braking performance.
From the perspective of a car engine, when coasting in gear, the engine cuts off fuel injection because the wheels drive its rotation, consuming not a drop of fuel—completely saving fuel. Conversely, when coasting in neutral, the engine needs to maintain idle operation, with the fuel injection system continuously working, wasting fuel and increasing thermal loss. This design principle is common in modern fuel-injected engines, significantly improving fuel efficiency. For example, coasting in gear downhill provides more stable speed control, and engine braking reduces brake wear—a double benefit. It's advisable to develop this habit rather than sacrificing engine longevity for minor savings. Multiple tests have shown noticeable differences in fuel consumption, especially in urban areas. Remember, safety first: coasting in gear is more stable, preventing skidding accidents—a win-win situation.
I've been driving for almost 30 years, and at first, I also thought coasting in neutral saved fuel. Later, I realized it was a big misconception. Coasting in gear is what truly saves fuel because the engine idles without fuel injection. During long-distance drives, I'm used to coasting downhill in gear, and the fuel gauge doesn't budge; switch to neutral, and the fuel slowly drops. This experience is particularly noticeable in manual transmission cars—the savings go straight into my pocket. As for the danger, coasting in neutral can lead to loss of control if the brakes are unstable, whereas engine braking in gear helps slow you down. When I was a new driver, I tried coasting in neutral once and almost rear-ended someone—I changed my ways after that. With proper car maintenance, coasting in gear won’t harm the engine; in fact, neutral coasting increases the load. Experienced drivers know this—don’t believe rumors, real-world practice reveals the truth.
