# Gas consumption while idling(parked)



## EatSleepRunBike (Mar 19, 2007)

How much gas does your car use while idling? How many hours per gallon would you get from a midsized SUV?


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## abvidledUK (Mar 19, 2007)

Enough to see the mpg figure go down on the display in my Jeep.


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## Brock (Mar 19, 2007)

I don't know about gassers, my TDI consumes about .22L per hour or .058 gallons or 7.5 oz of diesel per hour idling.


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## gadget_lover (Mar 19, 2007)

It seems this is not a figure that is often made public. I found several web sites that said 1 to 1.25 gallons per hour for an engine idling at 1000 rpm making 10 BHP.

I do know that my truck (F150) will seem to drink gallons per hour in a traffic jam, but my Prius will sip a few ounces under the same conditions. 

Daniel


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## Canuke (Mar 19, 2007)

In my Honda Civic hybrid, it's enough to see the MPG rating go down shortly after a fillup (I use one of the trip meters to track mileage so I can calculate mileage per tank accurately). On the other hand, the real-time MPG indicator maxes out at 120mpg at only 20 mph or so when I'm coasting in neutral, so I don't shut the engine off as some of the hardcore hypermilers do.


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## greenlight (Mar 19, 2007)

I hate it when I see people sitting in a parking lot with their engines running to power AC (*especially when it's 65' out). Don't they know we're at war for oil?


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## alaskawolf (Mar 20, 2007)

i go through a lot of gas having to idle my cars for hours during the winter months  

its getting close to April and we're still having -25F temps :mecry:


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## Cerbera (Mar 20, 2007)

alaskawolf said:


> i go through a lot of gas having to idle my cars for hours during the winter months
> 
> its getting close to April and we're still having -25F temps :mecry:



Sorry to hear that. I have an 1986 BMW E28 528e. The manual states that 3 minutes of idle is equivalent to 1 mile when driving. It seems pretty vague considering many variables can alter that claim. The only thing I can say is...don't idle.


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## alaskawolf (Mar 20, 2007)

yeah it sucks but its an unfortunate part of life up here  ive had my oil freeze solid after a few hours that i couldnt get the dip stick put, i had to put a pizza pan and bbq charcoal under a car for a few hours to thaw out the motor just to get it started again.


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## havand (Mar 20, 2007)

alaskawolf said:


> yeah it sucks but its an unfortunate part of life up here  ive had my oil freeze solid after a few hours that i couldnt get the dip stick put, i had to put a pizza pan and bbq charcoal under a car for a few hours to thaw out the motor just to get it started again.



At what point would it be cheaper to build a garage? I realize it would be expensive to fully heat it, but just a little bit could keep it warm enough.


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## 2xTrinity (Mar 20, 2007)

One point that's important to keep in mind is that idling fuel consumption will vary dramatically with temperature on most modern cars. A cold engine will often burn about triple what a "warmed up" engine will on most modern cars. Also, pollution will be a lot worse in the case of the cold engine. Generally it is best just to warm up a car by driving it lightly the first few minutes, rather than starting it and letting it sit several minutes. In a place that's very cold, an engine block heater on a timer is probably a good idea.


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## alaskawolf (Mar 20, 2007)

havand said:


> At what point would it be cheaper to build a garage? I realize it would be expensive to fully heat it, but just a little bit could keep it warm enough.


i rent a cabin so i cant build my own garage here and going out to the stores, movies,friends,etc and such doesnt really give you much of an option  ive got engine block heaters,oil pan heaters,battery heaters etc and i cant plug in every where i go either


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## greg_in_canada (Mar 20, 2007)

Have you tried Mobil 0w30 or is that with 0w30 oil?

Greg


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## goldenlight (Mar 20, 2007)

2xTrinity said:


> One point that's important to keep in mind is that idling fuel consumption will vary dramatically with temperature on most modern cars. A cold engine will often burn about triple what a "warmed up" engine will on most modern cars. Also, pollution will be a lot worse in the case of the cold engine. Generally it is best just to warm up a car by driving it lightly the first few minutes, rather than starting it and letting it sit several minutes. In a place that's very cold, an engine block heater on a timer is probably a good idea.



I have both an engine block heater, and an oil pan heater. I've learned that it's MUCH cheaper to heat the engine up with electricity, than start it dead cold, and get poor mileage driving it while it warms up. This works in even 'mild' winter weather, when I turn on the heaters from inside the house, so they may only be on 30 min to an hour.


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## alaskawolf (Mar 20, 2007)

greg_in_canada said:


> Have you tried Mobil 0w30 or is that with 0w30 oil?
> 
> Greg


 
i perfer to use Amsoil 0W oils in winter time


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## cobb (Mar 20, 2007)

My scion xa says to not idle it. DOnt prehaeat it, just crank it and go. I woul didle my diesel mercedes for heat or in slowly moving traffic with no problems. With my van I had e250, it sucked the same amount of gas running down the higyway or idling.


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## springnr (Mar 20, 2007)

Fuel injectors meter out the needed gas...with carburetors extended idling was not a good idea.


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## gadget_lover (Mar 20, 2007)

Extended idling is not a good idea in many car models. There was a mercury model (cougar???) that was not supposed to idle for more than 15 minutes. More than that could cause overheating problems.

Then there was the VW model that did not pump enough oil to the bottem end if it was at idle for extended periods. Was that the 1970's rabbit? I've forgotten.

All the modern cars advise that you start up and drive away without waiting for things to warm up. Modern oils do a good enough job of lubricating and circulating when cold. Modern fuel systems regulate the fuel mixture much better than the old mechanical choke did.

I once had a car that HAD to heat up, otherwise it would stall at the first light. Those were the days.

Daniel


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## Alin10123 (Mar 21, 2007)

abvidledUK said:


> Enough to see the mpg figure go down on the display in my Jeep.



LOL,
That's because when you are idling you aren't moving. So what happens is when the display calculates how many miles vs how many gallons yo've burned, it actually comes out instantaneously to 0. But your mpg figure will give you an average which will then bring down everything.


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## Lightmeup (Mar 21, 2007)

alaskawolf said:


> i perfer to use Amsoil 0W oils in winter time


Are you saying that Amsoil 0W will freeze solid on you?

BTW, I have read that if you are idling, like at a train crossing, etc., that it only takes 10 seconds to use up the gas it would take to restart the engine if you had turned it off. So, turning it off in those instances probably saves you quite a bit of gas.


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## gadget_lover (Mar 21, 2007)

There are problems with killing the engine each time you stop. In most cars, anyway.

First is the wear and tear on the starter. The standard starter has a fairly short lifespan. It's not unusual for them to wear out in only 10 years under normal use. Add 10 times the usage and the time between failure may become unacceptable.

Second is the drain on the battery. The modern car often has a battery that is just barely big enough. In stop and go driving you may run down the battery if you stop it every time you come to a stop. Even if it does not go dead, the deeper discharge may cause it to die early.

The hybrids are designed with these problems in mind. The higher capacity battery pack can handle the drain, and the motors are rated for 100% duty cycle. A great deal of their fuel savings happen when they stop the motor at stop signs and other times that it's not needed.

Daniel


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## paulr (Mar 21, 2007)

I've heard of electrically heated dip sticks. You just stick them into the oil hole and they warm up the engine. I'd imagine you could even put on one a timer to start warming the engine an hour or so before you wake up, instead of leaving it running all night.


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## alaskawolf (Mar 21, 2007)

Lightmeup said:


> Are you saying that Amsoil 0W will freeze solid on you?
> 
> .


 
yes it has at -50F and colder


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## Lightmeup (Mar 21, 2007)

gadget_lover said:


> There are problems with killing the engine each time you stop. In most cars, anyway.
> 
> First is the wear and tear on the starter. The standard starter has a fairly short lifespan. It's not unusual for them to wear out in only 10 years under normal use. Add 10 times the usage and the time between failure may become unacceptable.
> 
> ...


I say the tradeoff depends on how long you're going to idle and how often you do it. Battery systems are designed to handle this, I don't see the problem there. Got any links?


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## gadget_lover (Mar 21, 2007)

Links to the problems with killing the engine?

Ther was an article in either pop sci or pop mechanics in the late 1990's that explained the whole thing. It pointed out that the average driver could conserve a lot (I don't remember how much) if their cars were set up to handle killing and restarting the engines. I'm pretty sure that's the definition of a mild hybrid. Detroit was supposedly working on a standard for lights, radios, etc so that they would handle the increased voltage.

The article talked at length about one solution, and that is to use 24volt to 48 volt systems. The higher voltage prevents damage to the batteries caused by excessive current/depletion. The second component is an integrated flywheel / starter / generator. The concept could be integrated into virtually every car's current design.

The reason for the integrated flywheel / starter / generator is threefold. It saves space to use the flywheel. It allows you to spin the engine up to speed instantaneously when you push the gas pedal since it is always enganged (no bendix gears) . It allows a bigger generator to replenish the battery quicker.

I don't understand why this has not been done en mass. If it's patents that are blocking progress, then maybe the govenment should simply appropriate the patents via some national security/public good mandate. It's not like it's not an obvious idea. The only reason it was not a standard feature 50 years ago is the lack of controling electronics and fuel ejectors to make it clean.


Daniel


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## gadget_lover (Mar 21, 2007)

See the last two paragraphs of this article for mention of the 42 volt standard.

Dan

http://www.popsci.com/popsci/printe...efcd3bcc2eb84010vgnvcm1000004eecbccdrcrd.html


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## Eugene (Mar 21, 2007)

The 42volt systems are starting to appear in vehicles already. Another of the reasons for it is to have a mild hybrid you need something to keep other systems running when the engine stops. So you are now going to see vehicles with electric power steering and electric brake boosters and throttle by wire.


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## cobb (Mar 21, 2007)

I think the cold starting and drive my old mercedes 5 miles 3 times a day helped to kill it. Went through 2 sets of glow plugs, a battery and to rod noise. Maybe the use of starting fluid screwed it up, but if it aint got enough compression to start on its own with new plugs, its shot to begin with.


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## chevrofreak (Mar 25, 2007)

greenlight said:


> I hate it when I see people sitting in a parking lot with their engines running to power AC (*especially when it's 65' out). Don't they know we're at war for oil?



I hate it when people judge my actions because I don't want to bake to death inside my vehicle in the hot summer sun while waiting for something/someone.

I also hate it when people say this war is about oil.


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## iNDiGLo (Mar 25, 2007)

greenlight said:


> I hate it when I see people sitting in a parking lot with their engines running to power AC (*especially when it's 65' out). Don't they know we're at war for oil?



Last time i checked i decided how to spend my money. To each his own i suppose.


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## Norm (Mar 25, 2007)

alaskawolf said:


> i perfer to use Amsoil 0W oils in winter time


I prefer to live were these problems are unheard of. 
Norm


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## cbxer55 (Mar 26, 2007)

My 2006 Suzuki M109R motorcycle owners manual recommends a few minutes of warm up prior to riding.
Also strange is the oil level check technique. It is a semi-dry sump engine so this has to be followed to insure accuracy.
"Idle engine for 15 minutes, shut off and keep vehicle vertical for 3 minutes, Check oil at this time with bike vertical." 
So I simply check the oil level upon returning from a ride with the engine already warm.
If you are driving your vehicle really short distances it is better to warm it up before driving. Really short distance driving causes problems like rust in the exhaust system, contaminants in the oil that do not burn off because theoil did not get hot enough. The detergent in oil only works when the oil reachs operating temp. It is highly recommended that oil reach operating temperature and stay there for at least 15 minutes. If you are not doing this, change your oil more frequently than 3000 miles.
The catalytic converter does not operate until it is hot. Driving with the cat cold causes more pollution than idling it for a few minutes to get things hot.

THIS WAR IS NOT ABOUT OIL!!!!
GEEZ, some people.


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## alaskawolf (Mar 26, 2007)

Norm said:


> I prefer to live were these problems are unheard of.
> Norm


 
lets trade locations  its -26F right now :hairpull: my car is plugged in too


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## MarNav1 (Mar 30, 2007)

I think your average M1 Abrams gets about 3-4 gallons per mile, where's the dealer
ship? Parked? Who knows? No wonder diesel is so expensive!


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## gadget_lover (Mar 30, 2007)

> The catalytic converter does not operate until it is hot. Driving with the cat cold causes more pollution than idling it for a few minutes to get things hot.



While there is a grain of truth there, it works the other way.

Yes, the engine runs richer when cold, and the cat converter has to heat up before it starts to work efficiently. The average car produces more polution in the first few minutes than it does for the rest of a short trip. BUT... Running at idle for a few minutes will burn the same gas as if you were driving slowly without getting any benefit since it is not moving the car at all. It's just 100% wasted energy.

So the "experts" have advised for quite a while that a fuel injected, catalytic converter equiped car be driven without sitting at idle first. The only warm up needed is the few seconds it takes to buckle the seatbelt and back up.

I just woke up, so I didn't bother to look up any links to the experts.... Maybe later.


Daniel


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## 2xTrinity (Mar 30, 2007)

gadget_lover said:


> While there is a grain of truth there, it works the other way.
> 
> Yes, the engine runs richer when cold, and the cat converter has to heat up before it starts to work efficiently. The average car produces more polution in the first few minutes than it does for the rest of a short trip. BUT... Running at idle for a few minutes will burn the same gas as if you were driving slowly without getting any benefit since it is not moving the car at all. It's just 100% wasted energy.
> 
> ...


Anther point is that while letting the car sit and idle will warm it up, none of the other components -- such as the bearings, transmission, and other moving parts get warmed up in the process -- so there will still be a bit of a loss of efficiency until all those get warmed up too (whcih requires the vehicle to be moving). I've read from many sources what you just said -- light driving is the most efficient way to warm up the engine, as the same total amount of gas/heat is needed for the engine to warm up, but when moving, at least some of that is being put to use.



> I hate it when people judge my actions because I don't want to bake to death inside my vehicle in the hot summer sun while waiting for something/someone.


I agree with this. Honestly I see this as more of a fault of the auto manufacturers than anything -- there is no reason that people should have to idle continuously to keep from baking in hot cars.

Implement the engine start/stop system on a wide scale would make a huge difference. In addition to the ability for the engine to shut itself off at idle, it can also start and stop in "pulses" as needed to run air conditoining compressors, or heaters, or recharge batteries -- these pulses are a lot more efficient than running the engine at partial load continuously. 

Also, cars really shoudl be designed so they don't get as hot in the first place -- such as coating windows to block all IR, and implementing better circulation systems that allow more airflow. These are the sort of things that bother me about modern cars.


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## MarNav1 (Mar 31, 2007)

Guys there is no shortage and there never was. Idle your Hemi all you want! You may as well ask how much fuel a C5a uses while idling? Or Columbia? How about a weedeater?


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## cbxer55 (Mar 31, 2007)

Its all a moot point to me. Since I started driving I have done the warm up thing. That is 30 years now. You do not change what you have been doing for 30 years because some "EXPERT" says it is not a good thing! 
F--- the EXPERT!  
I warm my vehicle up until I see the temperature gauge needle start to move, then go driving. Always have, always will. My motorcycle has a converter, and when it says to warm up for a few minutes before operating, I believe I will do what the owners manual states, not what the "EXPERT" thinks I should do.
During the winter, I start my car up 10 minutes before I am ready to leave. Then go out and turn the heater on and let it run another 5 minutes. Nice and toasty when I get in to go.:thumbsup: 
My vehicle is a 1998 Ford Ranger V-6 with too many performance mods ro list, requires the use of 93 octane to prevent pinging. I still don'r have a problem letting it warm up.

OLD HABITS DIE HARD!

Mu advice to the expert.


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## cobb (Apr 1, 2007)

Id do what the owner manuals says. My scion xa sayd not to idle or warm it up, just drive. My benz said something about warming it up and different settings for idle adjustment and throttle position for starting. The benzes with the automatic would lock out certan gears to allow it to warm up quicker. 

Regardless, my scion warms up as i leave my driveway.


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