Coast in-neutral vs in-gear: I've been challenged to show the numbers

[turbovr41991]

I have been getting better gas mileage using DFCO in gear coasting with a pulse and glide technique. Better than what I was getting with engine running coasting pulse and glide. EOC is by far the best, but there are very few places n my commute where this would make sense.

[roosterk0031]

Been messing with the Cobalt using engine braking, it goes open loop and gph goes from 0.31 at idle (ac off) to over 0.5 after releasing clutch with heavy engine braking, takes 5+ seconds for it to go DFFO if it does and then doesn't stay in it for long. Neutral coasting is way better, the factory gauge is only 2 digits, so wouldn't have known the difference without the SGII.

Edit: Paid a little more attention on the way home, if I crest a hill and leave it in 5th, after about 5 secons it goes Open loop, and up to 0.4 gph for about 5 more seconds, then goes into DFCO for about 5 more seconds (smallish Iowa hill, maybe 3% grade, 100' fall) then back to closed loop. Pretty sure Neutral Coasting would account for better FE.

[GRU]

If someone is going to compaire the 2 techniques then they also need to change the driving style...example: if you start to coast in neutral at the same point of the road where you would when in gear then you are actualy using more fuel, so in order to use less fuel you can, and need to start coasting in neutral earlier than you would when in gear...
Its hard to explain but im just trying to create a scenario where someone is aproaching a stop sign or a red light

[ksa8907]

Originally Posted by GRU

If someone is going to compaire the 2 techniques then they also need to change the driving style...example: if you start to coast in neutral at the same point of the road where you would when in gear then you are actualy using more fuel, so in order to use less fuel you can, and need to start coasting in neutral earlier than you would when in gear...
Its hard to explain but im just trying to create a scenario where someone is aproaching a stop sign or a red light

Yeah, if I drive "normal" I would let off the gas about a quarter mile out, in neutral it would be more like a mile out.

[UltArc]

I hope that person who said all fire trucks are red was joking.
That's not a constant, lol. Honestly, very little is constant.
The sky is always blue- what about a sunset or sunrise?
Gravity is always the same- it changes with elevation and location.

So maybe there vehicle, combined with their location, their traffic, driving style, and gerneral commute yield better results with that method.

I think it could be possible. I pulse and glidw from 74mph to 65mph, so I don't block traffic, and I only get to that speed by drafting. I was just thinking about taking a super compact car, say old Civic and putting a huge engine in, with at least a six speed, if the engine can run at very low rpms and maintain speed. I can often get 35-40mpg on my commute, but I stop at a light then I drop .1 rpm about every 5 seconds.

I don't know if I am clear, but my basic point is for ones own unique circumstances, it may be possible. But your point does appear to be more probable, if you use X fuel to get to a speed, and have Y friction, you travel a distance. If Y increase, auch as engine drag, over that limited area, mpg SHOULD be lower.

EDIT:

http://my.firefighternation.com/grou...age=2#comments

[Fat Charlie]

I hope you're joking. The OP was asked to "prove" that coasting in neutral is more efficient than engine braking. If reb01501's challenger wanted data specific to his car and terrain then he shouldn't have asked someone to check the internet for data.

I've seen fire trucks in yellow, brown and woodland camo, but if my kid asks me what color fire trucks are I wouldn't say "it depends."

[UltArc]

Originally Posted by Fat Charlie

I hope you're joking. The OP was asked to "prove" that coasting in neutral is more efficient than engine braking. If reb01501's challenger wanted data specific to his car and terrain then he shouldn't have asked someone to check the internet for data.

I've seen fire trucks in yellow, brown and woodland camo, but if my kid asks me what color fire trucks are I wouldn't say "it depends."

Are you asking if my post was a joke? I am not super critical serious, but nothing was meant as a joke. And I didn't know he was asked to "prove" it, did he tell you that over a PM? I didn't see that anywhere, it seemed like a civilized debate, not so much an argument or anything hostile. And I'm not sure if they were asking reb about their car. It seems more likely they are only familiar with their own car, and they would expect others to have a similar experience.

I see, about your child. I don't have any children, but I'd say usually they are red, but you can paint it any color.

[reb01501]

Not "prove" ... provide evidence to back up the assertion. There is a difference. I in no way believe that a few test result will provide absolute proof of the assertion. All it takes is one contrary result to disprove it. However, the lack of negative results is telling.

[jsatter]

Originally Posted by euromodder

It's hardly possible to get decent numbers in normal driving, as you can't even start measuring from the spot where the coasting starts.

It'd have to be measured between a spot where one enters with X mph, and a place where one has to turn off at Y mph - that'd have to be reachable by coasting.

I started coasting shortly after joining ecomodder.
Coasting (even in neutral with the engine on) is what got me consistently below 5L/100km / over 47 mpg.
Up to then, I was avidly using engine braking, and only once in 5 years got below 5L/100km / over 47 mpg.


People are easily misled by the fact that their engine doesn't use gas when decelerating and letting of the gas pedal.
They don't realize they are also going to stop far, far sooner

You have to be on the gas longer to reach a coast point too. You lose on both ends when you coast in gear.

[RiceCake]

Most people start coasting before coming to a stop, in that situation in gear will only be beneficial (engine doesn't need fuel to idle, free braking from the engine, etc).

Hypermiling is an entirely different ballpark so complaining that one is better then the other is apples and oranges. It also matters between cars and a lot of things.

Everyone argueing its "obvious" what the solution is is being shortsighted and ignorant. Test it and post your test conditions, your car, and your results.