Coast in gear or in neutral?

[jacksmash]

Hey, I'm new here. Just picked up a new 2017 LX Sedan (6MT). Love it! Haven't owned a Civic since I sold my 2015 a few years ago. This really is a joy to drive.

Anyhow, back in the day I would coast in neutral will going downhill. Seems I now find mixed opinions about this when Googling. When trying it with my new LX, I do notice that my km/100L definitely decreases, but the efficiency indicators remain white; seems like a contradiction.

Thanks for any help with this.

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[coderdood]

I don't know for sure about this version of the civic but most cars implement a fuel cutoff strategy of some sort when coasting. This is an old article

http://www.caranddriver.com/feature...ng-to-a-stop-do-not-shift-into-neutral-page-3

 

[CivicChina]

always in gear

 

[phdninja]

I shift to neutral if I'm alone on the road, if there are other cars around I stay in gear if I need to make any adjustments quickly

 

[myke]

I coast in neutral all the time with my 6MT. Traffic light 1/4 - 1/2 mile up ahead... pop it in neutral... it's amazing how long it will coast and maintain speed. I did it all the time for 10 years in my Accord 5MT.

Don't worry about the efficiency meter; it thinks you are stopped because it's neutral. Also, when I coast in gear the meter turns white eventually yet my mpg indicator is at 80mpg. Wish I could turn off that meter in my LX... If anyone knows how, let me know!

 

[zroger73]

I don't know for sure about this version of the civic but most cars implement a fuel cutoff strategy of some sort when coasting. This is an old article

http://www.caranddriver.com/feature...ng-to-a-stop-do-not-shift-into-neutral-page-3

DFCO (Deceleration Fuel Cut-Off) was patented in 1961 for carbureted engines and is standard operating logic in most fuel-injected engines.

https://www.google.com/patents/US2993484

Also, it is illegal in many states to coast in neutral under various conditions. Here in Texas, for example, it is illegal to coast in neutral on a downgrade.

http://codes.findlaw.com/tx/transportation-code/transp-sect-545-406.html

 

[TheCodifier]

To me, it's not even a question. I always coast in gear.

Coasting in gear means the engine uses zero fuel. Being in neutral would require some fuel to maintain idle. Added to the fact that being in gear adds some resistance that helps maintaining speed on a downgrade. I even put it in S sometimes to help control the speed further depending on the grade. Being in neutral, the speed would increase past the speed limit.

 

[myke]

^^ What is 'S'?

 

[coderdood]

^^ What is 'S'?

I believe it is sport mode where the transmission tries to keep the engine revs higher

 

[Monocacy]

. . . Also, it is illegal in many states to coast in neutral under various conditions. Here in Texas, for example, it is illegal to coast in neutral on a downgrade.

http://codes.findlaw.com/tx/transportation-code/transp-sect-545-406.html

Just curious - is that limited to truck drivers, or does it apply to any vehicle?

. . . Coasting in gear means the engine uses zero fuel. Being in neutral would require some fuel to maintain idle. . . .

Wouldn't the engine cut off if zero fuel? I thought vacuum from the pistons would draw in some fuel (but maybe my brain is still in carburetor world).

I am genuinely interested in whether the engine uses less fuel in neutral or in gear. I would have assumed that coasting in neutral would be more fuel-efficient.

Anyway, I have long been in the habit of coasting in neutral. The only trick is to be cognizant of your speed so you can quickly choose the right gear if needed.

 

[Old guy]

Here's what Popular Mechanics says.

http://www.popularmechanics.com/cars/how-to/a2270/4230705/

The short and sweet is you would use fuel in neutral, you don't when in gear, just like @TheCodifier said

 

[zroger73]

Just curious - is that limited to truck drivers, or does it apply to any vehicle?

Per the link I posted:

"(a) An operator moving on a downgrade may not coast with the gears or transmission of the vehicle in neutral.

(b) An operator of a truck, tractor, or bus moving on a downgrade may not coast with the clutch disengaged."

Wouldn't the engine cut off if zero fuel? I thought vacuum from the pistons would draw in some fuel (but maybe my brain is still in carburetor world).

The engine keeps spinning because power flows backwards from the wheels through the transmission to the engine. There's not enough vacuum to "suck" fuel through injectors - they have to be on before fuel will flow through them.

 

[Monocacy]

Old Guy and zroger73, thank you both very much. I learned something new, and I love learning new things. Now I just need to break a 30-year habit.

 

[myke]

To me, it's not even a question. I always coast in gear.

Coasting in gear means the engine uses zero fuel. Being in neutral would require some fuel to maintain idle. Added to the fact that being in gear adds some resistance that helps maintaining speed on a downgrade. I even put it in S sometimes to help control the speed further depending on the grade. Being in neutral, the speed would increase past the speed limit.

I believe it is sport mode where the transmission tries to keep the engine revs higher

Well then that's the automatic tranny and not even relevant. You can't coast in neutral in an auto, I would never do that. This discussion is about the manual tranny...

 

[Shankmeyster]

Better than a double foot habit. Seeing people driving around here with the brake pedal pressed all the time drives me insane.

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