Does coasting in neutral or coasting in gear save more gas? - Fuel Economy, Hypermiling, EcoModding News and Forum

xbUser · 07-15-2008, 01:33 AM

For anyone has scangauge, would you please post the instant MPG when you are coasting in gear and coasting in neutral?

Someone says coasting in gear saves more gas because the injection system cut off gas. If so, should scangauge show very high mpg? (999mpg) If not, does coasting in gear save more gas than coasting in neutral? by how much?

Blue07CivicEX · 07-15-2008, 01:45 AM

On my civic coasting in gear cuts of fuel (9999mpg) but it causes drag and will reduce the distance you can coast, coasting in neutral results in between 100 and 300mpg but you are free-wheeling and get better distance. When I am coming to an offramp, stop sign, yield, stop light etc. I will use in gear coasting (engine breaking) to slow down and use 0 fuel but if I am coasting down a hill I will put the car in neutral to extend the distance of my coast.

I hope this helps!

SVOboy · 07-15-2008, 01:49 AM

Is this an auto? I think it'll depend on each transmission, but coasting in gear should cut fuel if you can feel it engine braking.

xbUser · 07-15-2008, 02:17 AM

Blue07CivicEX: "coasting in neutral results in between 100 and 300mpg"
Does higher speed result higher mpg? (by common sense) 300mpg is coasting in freeway, 100mpg is coasting in city?

brucey · 07-15-2008, 02:36 AM

Mines similar according to scangauge. Unless I know I'm slowing down, I leave it in neutral for coasts. My transmission takes a while to activate fuel cell, or scangauge takes a while to read it, and even then its pretty select as to when: Above 1200 rpm, slowing down, below 3600 rpm, etc

I tend to be in neutral a lot more. Plus (D) also holds my glides back tremendously. I blame it on the 4.44 final drive.

Arminius · 07-15-2008, 03:52 AM

Quote:

Originally Posted by xbUser

Blue07CivicEX: "coasting in neutral results in between 100 and 300mpg"
Does higher speed result higher mpg? (by common sense) 300mpg is coasting in freeway, 100mpg is coasting in city?

The SG will show higher mpg the faster you are going at the time. Keep it in gear when you are expecting to stop or need to slow down. If you coast at high speeds, its not unusual to get mpg in the high 100's and low 200's.

The last leg of my trip home is a level length of road that is 1.2 miles and that ends going down a small hill. I get my car up to speed, shift it into neutral, turn the engine off and coast into my garage at the very end. If I kept my engine running, the SG would probably show my mpg at around 170-200 at the beginning, and around 69 mpg just before I reach my driveway. However, with my engine off the SG does not work.

rsx2002 · 07-15-2008, 04:46 AM

i think you are supposed to turn the key back so that the accessories are on when you do EOC. that way the scangauge still works. other than that i agree with all the info you guys gave him its all the same for me.

Twerp · 07-15-2008, 04:57 AM

If you do EOC, you should put the SG in hybrid mode. Then, after you turn the engine off, turn the accessories back on. The gauge will read that you are burning a very small amount of fuel and your mileage will read around 1,000 mpg or so, give or take about 500mpg depending on speed. It may not be super accurate, but it will be better than letting the SG shut off during EOC.

PaleMelanesian · 07-15-2008, 11:12 AM

I don't consider in gear to be coasting at all. That's engine braking.

Coasting is in neutral, either EOC or engine on. EOC gives you infinite mpg, engine-on gives you high (100-300) mpg.

If you have to stop due to a red light, stop sign, or traffic backup, use engine braking where it cuts off the fuel flow. Any other time, go to neutral. The longer coasting distance easily overcomes the slight bit of idle-level fuel consumption.

The fuel consumption while the engine is off is related to a specific revision of scangauge. 3.15, I believe. Mine is an earlier one that reads an accurate 9999mpg in the same case, but it doesn't know about DFCO.

xbUser · 07-15-2008, 12:32 PM

If no traffic on the road, and you are not planning stop, is coasting in neutral better? Is it related to the driving speed, too?

Like, driving in city, coasting in gear can't coast too far because of 1) drag from engine, 2) room for speed reduction.(40mph to 30mph)

Driving in freeway may be different. 1) the motion of the vehicle is much higher (higher speed), that may overcome the drag from engine (especially on a deep downhill) 2) much larger room for "fuel cut period". (from 65mph to 30mph)

Am I right? Any opinion/correction?