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I was sitting in my van for about 40 minutes idling as I had to do some work on it, and noticed that it went from 11.9 l per 100 kms (19.7 us mpg)to 12.7l (18.5 us mpg)per 100km !!!! Holy crap, does idling in this van every suck gas hard !
I knew idling was bad, but that's a whopping difference in just 40mins of idling.
 

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I dont know exactly how much is used at idle. But remember you are getting 0mpg while idling. That can really lower your average quick.
 

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on average, figure between 1/2 gallon and 1 gallon per hour at idle on a 6 cylinder vehicle.

4 cylinders tend to be between .3 and .8 gallons per hour.
 

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I agree with the OP. When I went through a car wash, for instance, it seemed to me that the amount of fuel used during idle was excessive. Of course, I don't have hard data, but it just seems to me also that the Odyssey is using more fuel than it needs to at idle.
 

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and come to think of it for us who get temps below freezing or most of the time below zero................ we have to idle a bit more for morning warm ups!!!
 

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So you guys are basing this off the computer. Well if you are just sitting there it is going to take into its average that you are getting 0 mpg. Of course you are going to see a drop. It doesn't actually mean you are burning a sh1t load of gas. In my v8 5.7 Hemi it will go from 12.8 mpg to 8.2 mpg if I idle just for a few minutes.
 

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on average, figure between 1/2 gallon and 1 gallon per hour at idle on a 6 cylinder vehicle.

4 cylinders tend to be between .3 and .8 gallons per hour.
funny u write that, since i was just looking this stuff up and saw 4 cyl 's at .16 to .2 avg --wondering where u got your numbers
 

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funny u write that, since i was just looking this stuff up and saw 4 cyl 's at .16 to .2 avg --wondering where u got your numbers
I would say that it depends on engine displacement and compression. There are specific formulas for that kind of stuff.
 

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My Scangauge has the ability to display fuel consumption per unit time - gallons per hour or litres per hour. When I get home tonight, I'll let the van idle in the driveway for a minute and see how much gas it's sucking down just sitting there.
 

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OK - there it is. As you can see, the van was idling but not fully warmed up when I took this picture. The LPH in the bottom left corner stands for "litres per hour", so 2.11 L converts to about 0.56 US gallons. Because the engine isn't fully warm, the engine idle speed is still a little elevated here - I believe it's supposed to be somewhere around 700-750 rpms when everything is up to temp. So that fuel consumption might still come down a bit. I wouldn't have trouble believing that the actual value is probably right around 0.5 gallons per hour.
152897
 

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OK - there it is. As you can see, the van was idling but not fully warmed up when I took this picture. The LPH in the bottom left corner stands for "litres per hour", so 2.11 L converts to about 0.56 US gallons. Because the engine isn't fully warm, the engine idle speed is still a little elevated here - I believe it's supposed to be somewhere around 700-750 rpms when everything is up to temp. So that fuel consumption might still come down a bit. I wouldn't have trouble believing that the actual value is probably right around 0.5 gallons per hour.
View attachment 152897
thx for showing. Yeah, about what I'd guessed. I only thought about this very recently when for first time ever, I ran out of gas while idling in my '01 (and I quite often have operated with a low tank in recent years--even though I know it's not healthy for fuel pump, or I think it's not) Car doesn't get much use.
 

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You have to understand what the numbers actually mean. It doesn't mean you have actually burned almost a litre during that 40 minutes.

It is much easier to understand the concept if you look at the mpg figure instead, as your mpg will be exactly 0 when you are idling.

You will find the same thing on any car, as you will get exactly 0 mpg regardless of how much or how little gas the car used during idling. Do the math yourself you will understand better. What is the mpg if the van burned 200L in 40 minutes? And what about if it burned 1ml? Yes in both cases the mpg will be exactly 0.

Basically it's meaningless to talk about milage when you're idling.
 

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Where are you reading the MPG? At the trip meters? The way I understand it... the idle effect on the MPG shown on the trip meters will depend on how recently you reset the trip meters. If you travelled 200miles, that MPG will be weight averaged with the 0MPG at idle and have less effect on total MPG shown for the trip, compared with a situation where you just reset the trip meter 20 miles ago and then idled for an hour. Am I wrong?
 

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Guys, this is an 8 year old thread...

But yes, the effect that idling will have on your fuel economy is only in relation to how much time the van has also been moving. It is just total miles travelled (the M in MPG) divided by ( the P in MPG) the number of gallons burned (the G in MPG).

If you are getting 30mpg for 60 miles, you burned two gallons of gas. If you then idle long enough to burn 1 gallon of gas, your fuel economy will drop to 20mpg. If instead you got 30mpg for a 300 mile trip (10 gallons), idling enough to burn 1 gallon would only drop your mileage to 27.3mpg.

-Charlie
 

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Guys, this is an 8 year old thread...

But yes, the effect that idling will have on your fuel economy is only in relation to how much time the van has also been moving. It is just total miles travelled (the M in MPG) divided by ( the P in MPG) the number of gallons burned (the G in MPG).

If you are getting 30mpg for 60 miles, you burned two gallons of gas. If you then idle long enough to burn 1 gallon of gas, your fuel economy will drop to 20mpg. If instead you got 30mpg for a 300 mile trip (10 gallons), idling enough to burn 1 gallon would only drop your mileage to 27.3mpg.

-Charlie
It might be an 8-year old thread, but it gave me an excuse to play with my Scangauge, so I don't mind that at all. :D

With winter coming and temperatures dropping, getting people to think about just how much gas is consumed while idling is probably timely.
 
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