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Old 04-08-2011, 04:42 PM   #1 (permalink)
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EOC vs. neutral with engine on

Since joining this site I have learned some good hypermiling techniques. One I am just not grasping is the EOC. First off, I live in the hills of NE Tennessee so there are lots of hills on my commute to work. I tried EOC for the first time this week. I didn't mind the extra switch off, switch on. I did research and found how to install the kill switch and was about ready to gather the items needed when I started thinking: My car coasts at 650 RPM, which is idle. How much fuel can it use at idle? A quick web search revealed.....Not MUCH!! Something like 1/10 of a gallon an hour. That got me thinking about how much actual time I am in EOC. So for my 66 mile round trip commute I do not think it would be worth the time or effort. What do you think????

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Old 04-08-2011, 05:09 PM   #2 (permalink)
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I've done EOC with every vehicle I have owned with a manual transmission over the past 5 years.

I honestly think it does help quite a bit actually. Its not just about rolling up to a traffic light and leaving the engine off.

Rolling down hill can save you a lot. In spokane on division st there is a hill going back towards down town that is pretty steep. I held my speed at 30 and put it in neutral and shut it off as soon as I crested the hill. I was able to roll over a mile before having to stop for a traffic light. If the light had been green I probably would have been able to make it to the up hill stretch about 1/4 mile before the river bridge.

If it is a short down hill drop that is only about 50-100 ft before flattening out or going back up I will at least put it in neutral and use the momentum to keep me going. If the light turns yellow and I am close enough that I feel it is safe I give it a little bit more gas to get through the light...figure that short slight burst is more efficent than having to start from a stop again.

All those 2 block EOC's approaching a light, and 1 mile + stretches starting at the top of a hill all add up.

I find that I drive differently if I have no intention of shutting off at the light (In my wifes auto tranny kia). I keep my foot down approaching the intersection and brake much closer to the other cars waiting at the light.

Every car uses different ammounts at Idle. 1/10 of a gallon may apply to your car but is your car in like new condition? Mine is in great shape but I am fairly sure that being carbeurated and nearly 30 years old it uses a bit more at idle than it did brand new.

I am experimenting with my car to see how much of a difference there is between normal people driving and hypermiling.

Last tank I averaged 28mpg all city with 1 10 mile hwy trip.

Interested to see how much of a change I get on this current tank. I've already gone 50+ miles and the guage has not moved at all.

I found that there are roads that connect all sides of spokane so I can go anywhere I need to without even touching the hwy.
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Old 04-08-2011, 05:38 PM   #3 (permalink)
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A Scanguage will tell exactly what the difference is. It is substantial. It has been a while since I was into serious eoc hypermiling, but I would estimate that eoc can provide an increase in mpg of 10 to 20% of EPA over coasting in idle. It does take a lot of concentration and effort, so unless you enjoy the sport of it, you may be better off with coasting in idle.
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Old 04-08-2011, 05:43 PM   #4 (permalink)
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Except my scangauge turns off when the engine is off. Hard to get accurate figures that way. Of course engine-off doesn't work for me as I have an automatic, and diesel as well, using 0.1 gallons/hour in neutral. Engine-off would not save me significant fuel.
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Old 04-08-2011, 08:51 PM   #5 (permalink)
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.2 gph at idle,
coasting 1 mile at 60 mph (1 minute coast) with engine at idle consumes .0033 gallon

1 gallon / .0033= 303.

This means you would have to engine off coast for one mile 303 times to save a gallon.
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Old 04-08-2011, 09:02 PM   #6 (permalink)
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you can fix the SG, just put it into hybread mode, then it stays on.
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Old 04-08-2011, 10:00 PM   #7 (permalink)
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If you did a 50 mpg tank with EOC using the above numbers and coasted 100 miles of 500 miles (very easy to do if not a freeway commute) you save .3 gallons

10 gallons by 500 miles is 50mpg

if you did not EOC but neutral engine on coast instead.
10.3 gallons by 500 miles is 48.5mpg or worth 3% Definitely worth it in my book.

If you can coast more than that (I have had tanks with over 1/3 of my miles EOC) which has worked out to 200 miles EOC.

Much more likely average speed for EOC is 30mph which means .0066 gallons saved per mile. so at that you coast 150 miles to save a gallon.



11 gallons to go 500 miles is 45.5 mpg or a ~ 10% less than EOC
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Last edited by bestclimb; 04-09-2011 at 10:24 AM..
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Old 04-09-2011, 09:22 AM   #8 (permalink)
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Quote:
Originally Posted by BHarvey View Post
.2 gph at idle,
coasting 1 mile at 60 mph (1 minute coast) with engine at idle consumes .0033 gallon

1 gallon / .0033= 303.

This means you would have to engine off coast for one mile 303 times to save a gallon.
I was figuring about half of the fuel usage at .1 gallons per hour. My car is a 4 cyl. 5 speed that idles at 650 rpm, so I would have to coast 606 times to save 1 gallon. It just doesn't seem worth it, especially on the shorter coasts. Where the coast is over 1 mile maybe.

I don't have a Scangauge. My car is OBD0.

I did achieve my goal of 40MPG this week. I took a slightly longer but not as hilly route to work.
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Old 04-09-2011, 11:13 AM   #9 (permalink)
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The biggest gains are to be had by adjusting your driving to EOC, for example, accelerate to 45mph, cut engine, coast down to 30mph, bump start and accelerate to 45mph, repeat. Accelerate up hills, coast down hills.

With a Scangauge you get to watch your average mpg jump up while coasting with engine off, it is somewhat addicting, and there does not seem to be any other driving method that will give you as high mpg as EOC.
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Old 04-09-2011, 11:16 AM   #10 (permalink)
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his 1990 car won't accept a scan guage, MPGuino on the other hand... Would show him that his idle GPH is closer to .2 and how often his average coasting speed is well below 60mph and that it is far less than 303 miles to save a gallon.

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