Coast in gear or in neutral?

[zroger73]

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...

All automatic transmissions have a neutral position. There is nothing in the Civic's manual that says you aren't supposed to coast in neutral.

However, coasting in neutral with an automatic transmission is a bad idea for at least two reasons:

1) If the engine is not running, there's no pump to circulate fluid through the transmission for cooling and lubrication. This isn't an issue for a manual transmission.
2) It's illegal in many states as previously mentioned.

Supporting point number 1, the manual states that the vehicle should be towed either on a flatbed trailer or with the front wheels off the ground.

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

The days of being able to do that are numbered thanks to the brake-throttle override on most new vehicles with electronic throttle control, including our Civics. Pressing the brake pedal while in motion releases the throttle.

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[cestjoel]

The I had a 2009 Audi A4 automatic and it said do not put in N on down hills. Saying it would damage the catalytic converter. ‍

 

[jks]

It depends on the circumstances. I coast in neutral down a grade where I don't gain enough speed to exceed the speed limit. Yes I'm burning fuel, but I'm traveling maybe 40, 50, 60mph for the cost of idling which is very low--a great bargain. Coasting in gear saves idling fuel but the compression braking robs me of big gobs of kinetic energy which is poor fuel management. On the other hand, if the grade is steep enough that I would coast above the speed limit, it's better to compression brake in gear than coast in neutral and apply brakes--better from a fuel management standpoint anyway. The extra wear on the engine, transmission, and drivetrain parts from compression braking may outweigh fuel savings. Brake pads are cheaper than drivetrains.

In low traction situations (snow and ice) it may be better to brake to a stop in neutral and let the ABS manage traction for all the wheels than try to compression brake to a stop. Compression braking could cause the front wheels to skid which is very bad.

 

[myke]

All automatic transmissions have a neutral position. There is nothing in the Civic's manual that says you aren't supposed to coast in neutral.

Why would they even address that in the manual (guide, booklet I mean)? Makes no sense...

And the problem is shifting back into gear from neutral while moving with an auto tranny. If you want to ruin it, then feel free...

I don't think a car uses more fuel coasting in gear vs. neutral with the manual tranny, but you can coast for way longer in neutral and therefore use less gas...

 

[Monocacy]

I tested this today. No dramatic hills, but the fuel efficiency meter went to maximum whether I coasted downhill with the car in gear or in neutral. I did notice when coasting in neutral that the fuel efficiency started to drop well before I braked to a stop. I did not get a chance to see whether the same thing happened while braking in gear.

If the fuel efficiency remains at maximum while braking in gear, that could illustrate part of the (fairly minor) difference in fuel efficiency versus coasting in neutral. Well, assuming that you don't stall the engine.

The main take-home lesson is that it is very hard to break old habits. I actually had to think about shifting for the first time in decades. Thinking is haaaaard!

 

[turbo lover]

It depends on the circumstances. I coast in neutral down a grade where I don't gain enough speed to exceed the speed limit. Yes I'm burning fuel, but I'm traveling maybe 40, 50, 60mph for the cost of idling which is very low--a great bargain. Coasting in gear saves idling fuel but the compression braking robs me of big gobs of kinetic energy which is poor fuel management. On the other hand, if the grade is steep enough that I would coast above the speed limit, it's better to compression brake in gear than coast in neutral and apply brakes--better from a fuel management standpoint anyway.

The first person who I've seen in this thread who gets it. Coasting in gear means that there is a lot more friction, so while the car will burn zero fuel going down the hill, you will have to step back onto the accelerator as soon as your reach the bottom. Coasting in neutral lets your speed increase a little, but if you are alright with that then you can cost *much* farther before you need to step on the accelerator again. Overall, the fuel required to drive a certain distance is less if you coast in neutral, unless you need to stop at the bottom of the hill. Coasting in gear is usually only more efficient when you need braking force. Otherwise, neutral is the better option.

 

[T_A_H]

Coast in gear to maintain traction and ability to gas

 

[myke]

Huh, really? How exactly? What does 'switch it to maintenance reminder' mean? I'm talking about the white/green efficiency meter/light...

 

[jacksmash]

I believe he just means you can change the dash display to show maintenance reminder (or other things, like audio, etc.) instead of the fuel efficiency display. Obviously the efficiency lights at the top are there no matter what.

 

[Mikeybc]

Many trucking companies monitor the time a truck is out of gear and coasting...it is considered a huge NO-NO As far as engine braking in winter ... if your decelerating and engine braking is causing wheel slip you're in the wrong gear. It's never ever wise to coast in neutral.

 

[turbo lover]

Trucks rely a lot more on their engines for engine braking than our cars do.

 

[CivicChina]

Trucks rely a lot more on their engines for engine braking than our cars do.

because are driven by professionals who know how to use their vehicle

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