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What gets better gas mileage; stopping in gear or in neutral (manual trans)

Do you get better gas mileage coming to a stop in gear or in neutral with a manual trans?

I ask this question because in theory when you come to a stop in gear your fuel system partially shuts off using the kinetic energy to keep the engine running. Now I’m not sure if this is correct, so i wanted to get some opinions. Thanks.

It depends upon how long it takes and whether it interferes with safe driving. Generally, leaving a car in gear until it no long aids in braking while slowing down seems the safest and the least harmful to the trans mission. Then, just depressing the clutch is all that’s necessary.

Neutral will give you the best mpg, however In many states it’s actually illegal to cost in neutral for long periods of time. It’s feared if you need to accelerate suddenly you will be unable to in neutral. How would this ever be enforced is another question.

Best mpg? It can be different for various modern makes and models, depending on how the computer is programmed to control the fuel injectors as it senses the throttle position and the selected gear.

If you do find a satisfactory answer for your particular car, note that choosing the more economical method may save you as much as a nickel a day.

There is no universal answer. Buut the difference will be so small as to be incalculable…unless you’re driving a Bugatti Veyron. Or perhaps an Escallade.

However, unless your vehicle is designed for the engine to be shut off and restarted repeatedly, as some vehicles do automatically, you’ll prematurely wear out your starter motor.

By the way, those vehicles that aree designed to partially shut off the fuel supply don’t use inertial energy to keep running, the use the cylinders that they did NOT shut off to keep running. It really take little energy to keep a moder engine running at idle. The gas used ins miniscule. Today’s torque converters are so adept at dissipating the energy from an idling engine that they put no drag on the crank. Many will even roll backwards a bit if you take your foot off the gas while on an incline.

Engines that shut down completely when you stop are in hybrinds and use the stored energy in the battery packs to keep everything enabled and ready.

No measurable difference. Theories abound.

As mieich noted, No measurable difference.

the same mountainbike, I don’t see that there was any mention of shutting off and restarting the engine. Also, (just my opinion) I think all cylinders are shut down when coasting in gear, in some vehicles. The answer to the man’s question is “No measurable difference”…

Elly, you are correct. Mea Culpa.

But I did go into a bit more depth because the OP had a misunderstanding about the use of kinetic energy to keep running engines that are designed to shut down some cylinders when stopped.

I don’t think my '09 Caravan shuts down any cylinders when coasting, in gear, but I cannot tell.

The OP will save 100 X more gas by worrying about how they accelerate instead of how they coast up to a light.

Don’t worry about it!!