Which is More Fuel-Efficient: Coasting in Neutral or Coasting in Gear?
3 Answers
Coasting in gear is more fuel-efficient than coasting in neutral. Here’s a detailed explanation of why coasting in gear saves more fuel: 1. Coasting in Neutral: In modern fuel-injected vehicles, coasting in neutral is equivalent to idling. The engine continues to supply fuel, albeit less than during normal driving. 2. Coasting in Gear: When the engine is between low-speed fuel cutoff and high-speed fuel cutoff, the vehicle's computer detects that the car is in an idle state but the speed is higher than the engine RPM. In this scenario, the computer will cut off fuel supply to the engine, making coasting in gear more fuel-efficient. 3. Important Note: Manual transmission vehicles should not coast in neutral, as doing so can lead to insufficient lubrication in the transmission, resulting in wear and tear.
As a veteran driver with twenty years of experience, I find this topic quite worthy of discussion. From my experience, coasting in gear is noticeably more fuel-efficient. For example, when driving a manual transmission car downhill in fourth gear, although the engine RPM is high, the fuel supply is cut off, resulting in virtually zero fuel consumption; whereas coasting in neutral means the engine still consumes fuel at idle, costing a few extra cents per kilometer. Safety-wise, I also prefer coasting in gear—it provides engine braking to stabilize speed, especially on long downhill stretches. In my younger days, I tried coasting in neutral a few times, and indeed, fuel consumption was higher, plus the car felt unstable and floaty—just thinking about it now gives me chills. With automatic transmissions, it’s even simpler: just stay in Drive (D) to enjoy the fuel-saving benefits. Breaking the habit of coasting in neutral could save you hundreds of dollars in fuel annually.
I often enjoy sharing insights on car enthusiast forums, where many beginners ask about coasting to save fuel. The conclusion is clear: coasting in gear is the big winner! The principle is simple: when the car is moving fast enough and coasting in gear, the computer automatically cuts off fuel supply, resulting in zero fuel consumption; in neutral, the engine must keep running and consumes fuel. I've tested this with my own car using an OBD scanner tool—coasting in gear for one kilometer showed 0.0 liters of fuel consumption, while coasting in neutral could reach 0.5 liters. Don’t underestimate this small difference; on city roads, frequent coasting segments add up. Safety is also crucial—coasting in gear helps share the load with the braking system, avoiding the risk of losing control that comes with coasting in neutral. I recommend gradually getting used to coasting in gear—it’s both economical and reliable. Just remember to adjust the gear according to speed, as shifting too low at high speeds might damage the transmission.
