Is It More Efficient To Coast In Gear Or In Neutral?

Is it more fuel efficient to coast while in gear or in neutral? This is a question we’ve pondered in the past too, and thanks to Engineering Explained, we finally have an answer.

In the vast majority of modern cars with electronic fuel injection, Engineering Explained reveals that it is more fuel efficient to coast in gear than in neutral. Why? The answer is quite simple.

When you’re coasting down a hill with the car in gear, the engine no longer injects fuel. Consequently, the engine is consuming no fuel when rolling down a hill and is only turning over because the wheels and transmission are forcing it to.

On the other hand, if you were to coast in neutral, you’d use a little more fuel. This is because the engine requires fuel to keep a vehicle idling.

One scenario when coasting in neutral is more fuel efficient is when you roll down a large hill and have enough momentum to roll over a smaller hill while still in neutral. If you were to attempt this in gear, a car would use no fuel going down the first hill but the engine braking would force the driver to accelerate up the second hill, thus using more fuel.

VIDEO

  • LWOAP

    Lol. I already watched the dude’s video just the other day.

  • I DON’T DRIVE A STICK TO SAVE FUEL.
    WHEN COMING TO A STOP, ON LEVEL GROUND, I POP IT INTO NEUTRAL. ALSO WHEN COMING AROUND A CORNER WHERE I’LL NEED TO DOWNSHIFT. OTHERWISE I LEAVE IT IN GEAR.

    • benT

      “I DON’T DRIVE A STICK………….”

      you do to

  • benT

    safety requires that you coast IN GEAR !!

  • Tati Properties

    Actually my 2016 Volvo XC90 does the opposite. In ECO mode, between 38mph and 60mph, once you let go of the accelerator, the gearbox disconnects and the car coasts while idling. If the brake pedal is touched the car reconnects and slows with an engine-gearbox help as well. I’m sure they calculated the distance covered while rolling and idling is greater than if the car was rolling and gear braking. I’m sure a lot of calculation went into this thought by Volvo engineers and the most efficient way was picked.

  • I knew that.

  • LeStori

    Drive in angel gear and even if you save money, the funeral expenses are a real killer…

  • thunder bolt

    This is to save a little bit of gasoline? why?

    • Jason Miller

      Saves more than you think.

  • Craig

    Does he really mean NO FUEL AT ALL while coasting? If so – that’s amazing to me. And baffling. [I can’t seem to wrap my mind around it] So have all ‘explosions’ stopped? Is there no longer any fumes coming out of the exhaust?

    • Tati Properties

      Correct, fuel is only added when you push the accelerator or when the car is idling.

    • Guest

      Yes, no fuel at all when coasting in gear with enough rpm to not stall the engine. It’s because when in gear, wheels and engine are in fixed connection, so when you accelerate the wheels are being turned by the engine, but in reverse when you are not accelerating, momentum is running the vehicle, so then the wheels are running the engine, so the injectors can be shutdown.

      • Craig

        Thank you! Never to old to learn something new! That said… they should only build roads that go down hill. You know… to save fuel. [lol]

  • Vassilis

    I’ve also found that if you’re doing small speeds, coasting in gear does use some fuel while being in neutral uses a little less.

  • Blade t

    Interesting….

  • Zed68

    Anyway, going down in gear is much better for car control

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