Does coasting in neutral save fuel for manual transmissions now?
4 Answers
Coasting in neutral with a manual transmission does not necessarily save fuel and may even increase fuel consumption. The specific principles are as follows: 1. Many car models are equipped with electronic fuel injection systems. When the car shifts into neutral, the ECU defaults to the car being in an idle state, thereby increasing the fuel injection volume to maintain idle speed. 2. The electronic fuel injection control system itself has the function of reducing or cutting off fuel. Using neutral coasting at this time loses this function and increases fuel injection volume. The damage caused by coasting in neutral with a manual transmission is as follows: 1. Causes jerking; 2. Reduces braking efficiency; 3. Affects engine lifespan; 4. Transmission gears are prone to breakage.
In the past, coasting in neutral with old carburetor cars did save fuel, but now that I drive a manual transmission car, I've long stopped doing this. With fuel-injected cars, the ECU actively cuts off fuel supply when coasting in gear, bringing fuel consumption directly to zero; shifting to neutral instead consumes idle fuel, potentially wasting 50ml more over 10km. The most critical issue is losing engine braking downhill, which can overheat brake pads and cause failure. Last year while driving mountain roads, I tried coasting in gear - the instant fuel consumption gauge dropped to zero, proving much more efficient than neutral coasting. Nowadays, I basically never use neutral coasting except when waiting at long red lights.
Over the years of driving manual transmission, I've repeatedly confirmed that coasting in neutral doesn't save fuel. A car engineer friend explained with data: when coasting in gear, the wheels drive the engine rotation without fuel injection - coasting 500 meters at 80km/h can save half a can of cola's worth of fuel. In neutral, the engine must maintain 800rpm idle speed, continuously burning fuel. The worst part is emergency situations - braking distance during neutral coasting is a full car length longer than in-gear coasting. Last year during rain, I witnessed a rear-end collision in the next lane caused exactly this way.
This is a common question from car owners during repairs. To be clear, modern fuel-injected vehicles save more fuel when coasting in gear, as the ECU automatically cuts off fuel injection. Coasting in neutral requires the engine to burn fuel to maintain idle, causing more wear. As a reminder: those who frequently coast downhill in neutral need to replace brake pads every three months; those using engine braking by coasting in gear won't need replacements for half a year. From a safety perspective, the extra 5-6 meters braking distance in neutral can be fatal.
