Myth Busted: Idling wastes fuel!

Myth # 2: It takes more gas to restart your car than to keep it running. Shutting it off and starting it again is also very hard on the engine. (See the myth busted below)

Idling is one of the largest wastes of fuel for Canadian drivers and all of that waste is taking us nowhere. In fact you could be spending up to 25% of your time behind the wheel idling. Depending on your vehicle, every 10 minutes of idling is costing you between 1/10 and 4/10’s of a liter of fuel.

Idling is something we don’t often think about – it’s a habit that we do unconsciously. Reducing our idling not only saves us money, but reduces significantly greenhouse gas emissions (CO2) and health-harming pollution. If Canadian motorists reduced their idling by just 3 minutes a day, it would be the equivalent to taking 320,000 vehicles off the road for the entire year!

So do you need to be idling when you are:

  • dropping off or picking up kids school?
  • waiting at a drive-thru?
  • waiting in line at the gas station or car wash?
  • running short errands?
  • warming up car in cold weather?
  • stopped at railway crossings?
  • stopped at construction zones?
  • stopped at red lights?

Myth Busted

While the initial question may involve a “value judgement,” the answer is quite clear, idling wastes fuel and gets you nowhere! The fact is that:

  • anything over 10 seconds of idling uses more fuel that shutting off and restarting you vehicle.
  • the money you save by not idling will more than offset any costs for wear-and-tear on your vehicle.

One of the most important reasons for reduced idling is simply the cost. The fuel consumed in 10 minutes of idling varies between 1/3 and 1/2 of a litre depending on your particular vehicle. Today’s vehicles with fuel injection and electronic ignition start more easily and suffer far less wear and tear on the engine components. National Resources Canada indicates that the break even point to offset any potential maintenance costs is 60 seconds, however other research would indicate that 30 seconds would be more accurate. Some sources estimate the cost of restarting your engine to be approximately $ 10.00 to $ 15.00 per year, which would more that be offset by the fuel saving costs.

And let’s not forget about the idling that many of us do to warm up our cars in winter. The best way to warm you car up in winter is to drive it. Here is a video that clarifies the situation. The bottom line is that as long as you are using the correct viscosity oil, you are good to go.

Excessive idling can actually be more harmful for your car as the fuel is not fully combusted when your car is idling outside of its peak operating temperature. This fuel residue builds up on the cylinder walls and can also contaminate the engine oil thereby reducing its ability to lubricate. On most days you need no more than 30 seconds of idling before driving away. Your engine, and all the other components that do not warm up while idling, will warm up quicker and more efficiently.

So, the bottom line is that if you anticipate that you will be idling for more than around 30 seconds, other than when you are in traffic, it is best to shut your vehicle off and restart it. Excessive idling wastes money and produces unnecessary CO2 emissions which contribute to climate change. Oil reserves are dwindling, demand is increasing, and costs are rising so why waste this valuable resource going nowhere. Save money now and save the environment for the future!

For more myths, see our Green Myth Busting page.

64 Responses

  1. Bryan Althaus | July 20, 2015 | 4:12 pm | Reply

    Ford, BMW, Audi, Mazda all sell cars which automatically turn off their engines at stop-lights. It’s called Auto Stop-Start. Bosch even has Start-stop system with coasting mode!

    http://www.gizmag.com/tag/start-stop/

  2. David Cameron | July 11, 2015 | 1:51 am | Reply

    Many people have this misconception for this reason only they never turn off their vehicles. Thanks for sharing this valuable information.

  3. Eric S. | June 24, 2015 | 6:25 pm | Reply

    I’m surprised that nobody has raised the issue of the oil sump- that’s where gravity drains the engine oil down to when the motor is not running. Hot oil can take several minutes to drain back down into the sump once the engine is stopped, but the process begins the moment the engine is stopped.

    Every time you start an engine, there are inadequately-lubricated metal components that wear against each other until the oil from the sump circulates enough to adequately lubricate the engine. This process takes less than a minute, typically, during which much wear is done to the engine- metal can rub against metal, ejecting tiny metallic dust particulate all over your engine. This metal dust collects carbon deposits and makes your oil black instead of light brown. Also, the wearing-down of your engine components ruins the precise tolerances and can lead to “blow by”, stealing power and allowing hot cylinder gasses to escape into the oil and pollute it.

    Also, the heat-cycle of stopping-and-starting an engine causes additional wear to rubber seals and plastic parts and other components prone to become brittle from heating-and-cooling cycles.

    Personally, I avoid unnecessary idling, and I use 5 minutes as a general rule of thumb. If I think I’m likely to idle for over 5 minutes, I shut it down. Unless it’s freezing/hot outside, of course. My comfort comes first.

    Also, remember that at low RPM, the spark plugs are more likely to collect carbon deposits, leading to misfiring (although usually all you gotta do is put it in neutral and rev the engine near redline for 10 seconds to clear that up). Also remember that when you’re not moving, some components (like the transmission and exhaust) don’t receive any cooling from fresh ambient air running over them.

    • Dave Elmore | June 26, 2015 | 8:29 am | Reply

      All good points of which I would not to be n expert on, however I would offer up some discussion points to your comments. I would agree that it “can take several minutes to drain back down into the sump once the engine is stopped” and add that even after it has drained a thin film of oil would remain. As we are talking only about short periods of time to shut off your engine there would be adequate lubrication still remaining even if you had shut it off for “several minutes.” This would also in my mind apply to your second point about the component wear.

      The your point about “the heat cycle” I would also offer that we are talking about short time frames. The time for you engine to cool down completely one would hope no one would be considering leaving their engine running. I am glad to hear that generally you avoid idling unless it is “freezing/hot outside” but shutting down your engine for 5 minutes even in extreme temperatures does not result in uncomfortable conditions inside your car.

      To your final point about spark plugs and ambient air cooling of the transmission and exhaust I would again not claim to be an expert, however electronic ignition systems in today’s cars are so much superior to old system of coil and wires that I am not sure that the issue still applies. In terms of the other components, the ambient air cooling would only apply when the car is in motion and hopefully no one is turning off their engine while in motion.

      Thanks for your comments. As I have said several times we are not experts on motor vehicles, we simply are in many cases restating what experts have indicated regarding idling your car unnecessarily.

    • Brandon | July 18, 2015 | 1:21 pm | Reply

      Automatic transmissions usually have fluid to water coolers in the radiator, but the exhaust is a valid point. I know back in the 70s and 80s when catalysts were first hitting the production lines general motors advised to tap the accelerator every 5 minutes you idled to help combat exhaust system over heating

    • phyllis | April 21, 2016 | 9:25 pm | Reply

      It also depends whether you care more about your car’s components or peoples’ lungs.

  4. Amber | March 24, 2015 | 6:50 am | Reply

    Interesting article, and really good points. I have a question related to our car if you can help… We have a 1999 Golf estate with a push button start, and I have been having trouble finding out whether the wear and tear on this age car would be greater from starting and stopping the engine. We never idle for long anyway, but occasionally for a couple of minutes. We would rather save energy and money, but can’t afford our somewhat fragile car to fall apart. Any information would be appreciated, cheers.

    • Dave Elmore | March 24, 2015 | 8:19 pm | Reply

      We are by no means experts or motor vehicles and cannot possible know the specifics of your 1999 Golf, however as we stated in the blog, “today’s vehicles with fuel injection and electronic ignition start more easily and suffer far less wear and tear on the engine components.” I would assume that your vehicle is “new” enough to have both these but if you are unsure then a quick discussion with your mechanic will clear this up. Again as the blog points out “National Resources Canada indicates that the break even point to offset any potential maintenance costs is 60 seconds, however other research would indicate that 30 seconds would be more accurate. Some sources estimate the cost of restarting your engine to be approximately $ 10.00 to $ 15.00 per year, which would more that be offset by the fuel saving costs.”
      The bottom line is that modern vehicles start much more easily due to these modern components and thus do not cause the wear and tear that would have been expected in older vehicles with carburetors that required some time to deliver fuel to the engine and ignition systems that also required time to ignite the fuel.
      While this does not directly answer your question we hope that it none the less is helpful.

      • ITRobert | September 4, 2015 | 9:04 am | Reply

        Dave, please excuse me for not agreeing with your comment. We are in 2015 and the mentioned Golf is a 1999. This means a lot if you know cars. The battery is most likely not new (we don’t know that, I agree); it might have a hard time holding power between starting cycles; so is the 16 year old alternator – it might not charge enough between short driving cycles. The starter is basically an electric motor with brushes and it wears out; using it more often will shorten the life and the list can go on and on… You might find yourself saving 10 bucks on gas/year and spend a multiple on repairs. By all means I’m no advocate for idling or unnecessary fuel consumption, more so I’m doing all I can to get the best gas mileage I can and am proud doing so, but there is a fine line and also a balance between things. My idling goes way beyond 5 min. but again it depends on many factors and what works best for one person does not necessarily work for all…

        • Dave Elmore | March 10, 2016 | 6:02 pm | Reply

          I agree that there is always a question of wear and tear on the components when it comes to shutting off and restarting your car. The experts (of which I am not one) seem to agree that with modern technology (fuel injection and electronic ignition) the costs for wear and tear on your vehicle far outweigh the cost of idling for long time frames. That said, each car is different and we do not profess to be experts. In each case it is best to rely on experts and as I stated in my original response, “if you are unsure then a quick discussion with your mechanic.”
          Glad to hear that you are not an advocate of idling and we do appreciate your comments. As I said we are not experts, only advocates for reducing fuel consumption and the resulting emissions that go with them.

  5. Cory V | February 23, 2015 | 11:42 am | Reply

    While most of the information given here is all well and good, and I certainly agree that idling pointlessly (like at a RR crossing or while waiting on others) is a bad thing, I do have to disagree with not letting the car warm up. I drive an ’07 Fusion. During the winter, idling my car for 5 minutes in the morning uses about 1 mi of gas on my remaining mileage. I drive 7 miles to work, and it usually uses 7 miles worth of gas; total usage of 8 miles worth of gas on the fuel computer. If, on the other hand, I start the car and let it idle for just long enough to brush the snow off, then head into work without warming it up, I usually use 10-11 mi worth of gas due to how much richer it mixes the fuel to run while cold.

    Could you explain to me how I’m helping the environment by burning more fuel, and how burning more fuel helps my wallet?

    Additionally, it’s not just how much fuel is being burned, but the quality of the exhaust coming out of the tailpipe. A catalytic converter does almost nothing until it reaches internal temperatures of at least 550 F. Idling releases very little untreated exhaust into the envornment, and gives the catalytic converter time to warm up while releasing very few damaging compunds into the environment. On the other hand, if I’m actually driving my vehicle to warm it up, I’m burning significantly more fuel and therefore releasing much more untreated exhaust into the air until the catalytic converter can reach it’s optimum temperature, even if it warms up faster under load.

    Additionly, if I idle my car in the morning, I don’t have to freeze my butt off, because my car is already warm inside after 5 minutes as well.

    Can you explain to me what the benefits of using more fuel, releasing more untreated exhaust, and freezing my butt off for the first 5 minutes of my drive to work are, because none of that sounds beneficial to my wallet, the environment, or me?

    That being said, during the summer, when my car does not seem to mix the fuel significantly richer in the morning due to warmer temperatures, I rarely ever idle it, and in fact am usually on the road within a few seconds of starting it up.

    • Dave Elmore | February 23, 2015 | 12:56 pm | Reply

      Let me start off by saying I am not an expert of gas mileage monitoring systems, but from what I have read the opinions of their accuracy are certainly varied. I have checked the system in my Prius versus the old standard of calculating mileage based on the number of litres or gallons used over several full tanks of gas. Yes this way of calculating fuel consumption also have many potential flaws, however it has never really matched the fuel monitoring system. In my particular case the monitoring system indicated better fuel economy, which makes sense since it would be in the car makers best interest for us to believe that fuel economy of our vehicle was better than it actually was.

      I am not sure of what kind of monitoring system your Fusion has but the results indicated in a number of “miles worth of gas” is not something that I have seen on any vehicle I have driven. To respond to some of your questions however, I would agree that burning more fuel and releasing more untreated exhaust is not beneficial. If in fact your car is using more fuel driving as opposed to idling then it all makes sense, but I have to wonder why the vast majority of experts agree that idling wastes fuel. They also agree that your vehicle warms up faster driving it than idling it, and this includes the catalytic converter. There is no doubt that your car runs richer when it is cold, but again, if you can warm it up quicker it will stop running rich all that much sooner.

      Freezing your butt off of course is a personal preference and one that is really not part of how to reduce fuel consumption. It would seem to me that you should do a mileage check by the old standard method based on at least 2 or 3 tank fulls of gas and see how that compares to your fuel economy monitoring system. Of course it won’t really allow you to compare your short trip to work, but it will at least provide some confirmation of what you are seeing on your dash. One last point, I have found my the monitoring system in my Prius to be very unreliable when it comes to short distances. It is only when compared with longer distances that it has been somewhat more accurate.

  6. hmmmm | February 15, 2015 | 3:05 pm | Reply

    Don’t you guys have electric engine preheater in your car? Get it installed then. Of course it does not get the engine to the optimum running temperature, but it sure decreases the wear on the engine. On top of that it reduces hydrocarbon emissions, which in other words are unburnt fuel from the exhaust. It reduces the amount of fuel needed for the start.

    I’d say that turning off the engine for just 10 seconds is stupid thing to do unless the car has a robust starter with start&stop function and a gel battery. It’s just not worth it. I’d stop the car if i knew that i’d need to keep still longer than two minutes. But i rarely get that much advance information.

    • Dave Elmore | February 16, 2015 | 7:04 am | Reply

      Most all vehicles here in Canada and likely through the northern US would all have block heaters. I assume that is what you are referring to as an “electric engine preheater,” In a few of our other blogs including this one on “Idling not the best way to warm up your car” we recommend the use of block heaters. This will warm the oil somewhat and allow it to circulate more quickly thus making it possible to drive away sooner after starting, This would in turn of course reduce hydrocarbon emissions as you indicate because the engine would warm up quicker. As we wrote in the blog above “until your vehicle’s catalytic converter reaches peak operating temperature (between 400°C and 800°C), it does little to help reduce emissions.”

      While it is clear that turning off your engine if you are going to be stopped for more than 10 seconds will save fuel and reduce emissions, it is also clear that it is not always practical in traffic. That said,many people will idle there cars for long periods in situations where they can easily shut the engine off.

  7. George | February 7, 2015 | 9:11 am | Reply

    Interesting read, especially the comments. If you want to know how long to idle you car form a cold start just read your owners manual! It should be in there. My 2013 vehicle has a higher cold start engine RPM that last for about 1 minute regardless of the temperature outside (hot or cold). I use the RPM drop as my guide for when to drive away. Once the engines RPM drop there has been plenty of time to circulate the oil in the engine. If it is cold to the point the vehicle may seem a bit sluggish, I am light on the throttle. Luckily my car with a 1.4L turbocharged engine heats up very quickly thanks to the turbo. I have driven other cars where the engine RPM drop gradually changes while the engine gets up to operating temperature. We all should know that the best way to get up to operating temperature in modern gasoline engines is by driving, even if that is slowly for the first few minutes.

    • Dave Elmore | February 7, 2015 | 3:58 pm | Reply

      Interesting advice to look in the owners manual. My car’s manual only indicates that in extreme cold weather conditions to warm up the engine at idle and not with the accelerator depressed. Car companies could be offering better advice.

  8. Mitch S | February 4, 2015 | 7:40 pm | Reply

    What I do get here is you’re saying this applies to all vehicles. Now I drive an diesel f250 and on the really cold days here it barely runs when I first start it, and it takes a good 3 or 4 minutes for it to even warm up to a smooth idle. I won’t drive drive it until it at least starts running properly.

    Now I’ll admit I always let it idle longer but that’s just because I prefer to drive in a warm cab, not necessarily for the truck.

    Another thing is anyone who’s owned a turbo diesel knows CCAs are important to get those big engines started and even on brand new batteries having to turn the engine on and off too many times in cold weather without going for a good drive in between will just drain them.

    • Dave Elmore | February 6, 2015 | 1:56 pm | Reply

      I assume that you are driving an older model F150 and not a newer model with fuel injection. In that case you do need to idle longer to get it running smoothly before driving, however if that is not the case, you may need to get your vehicle serviced. Its been many years since I had to sit in my car with my foot on the gas just to keep it running.
      Your preference for a warm cab aside, the vehicle will definitely warm up quicker by driving it. You may want to look at our more recent blog on idling for more information.

      • Mitch S | February 21, 2015 | 11:14 am | Reply

        It’s not that old, 06 turbo diesel, so definitely fuel injected. It will run on it’s own no problem just not smoothly at first in extreme cold, even with the block heater plugged in, noticeably better with the block heater though. Part of that is because of the performance mods I’ve done to the engine.

        As for the warm cab, it definitely does warm up faster while driving but then I’m in the cold is all I was saying, I just prefer to use the remote start so that it is warm before I even have to go out of the house or leave work.

        • Dave Elmore | February 21, 2015 | 12:26 pm | Reply

          Diesels are a different animal for sure. As for the remote starter, they have become very common place because of the very reasons you mention. We are just saying it wastes fuel and adds to our already problematic CO2 levels.

      • Gary | February 24, 2016 | 11:43 am | Reply

        Dave, FYI, Diesel engines have always been fuel injected.

  9. oil | January 29, 2015 | 4:05 am | Reply

    Ordinarily I can’t read through content in sites, however I would like to point out that this specific write-up pretty much forced me to take a peek at it along with taking action! Cheers, extremely excellent write-up.

  10. TJ | January 14, 2015 | 8:17 pm | Reply

    This article is funny, try driving off after 30 seconds when its -15 your windows will ice up on the inside and outside, and your car will take forever to warm up especialy if you have a small 4cyl.

    In -20 it can take 20 min for the temp gauge to start to move, so your contradicting yourself

    • Dave Elmore | January 19, 2015 | 10:03 am | Reply

      Happy that you are finding humour in our post, however we are quite serious about idling. Idling is a waste of fuel and gets you nowhere. You many want to read our “Winter Driving Tips” to see how you can deal with the issue of moisture condensing on the windows. You may also want to read “Drive to warm up your car” to clarify why you do not need to warm up your car to full operating temperature and how idling can in fact be more harmful to your engine than driving.

      In response to your comment about it taking 20 minutes to warm up your vehicle at -20, the fact is it will warm up more quickly if you drive it. Its kind of like climate science, all the experts agree.

    • bn880 | January 27, 2015 | 10:08 am | Reply

      For cold winter starts it’s best (if possible) to use a block heater for 3-4 hours. That was you can drive off after 10 seconds of idling and not be frozen yourself or with frosted windows. Otherwise: people are going to warm up their cars …

      • Dave Elmore | January 28, 2015 | 11:06 am | Reply

        Agreed. We cover the use of block heaters in our Winter Driving Tips blog. Use of the block heater will significantly reduce the time it takes for your car to warm up. As it warms the oil in your engine it will also allow the oil to circulate all that much quicker which as you note allows you to drive away (driving gently of course) after only a short period of idling. Your windows may still fog up however if you follow the tips we have in our Winter Driving Tips blog you can minimize this issue.

  11. Grease monkey | January 6, 2015 | 1:11 pm | Reply

    I would rather idle my car. 5 min, 10 min, 15 min. All better than replacing a starter from excessive use. I also know for a fact that its best to let you car get to operating temperature before you drive. This allows proper lubrication in ALL components of your vehicle. Not just engine oil. Yea it’s a waste of gas. Ya it’s pollution. But the fact is, no vehicle is free from it. The problem is not that you idle your vehicle. The problem is that we have no real clean option to a car.

    • Dave Elmore | January 12, 2015 | 11:01 am | Reply

      Old habits are hard to break and misconceptions about idling to warm up your car persist. Auto experts today agree that in most cases you need no more than 30 seconds of idling, especially if you have your car plugged in. The engine will warm up faster being driven than sitting running in your driveway and idling will not warm up “all the components” of your car. Driving your car allows other drive train components like your transmission to warm up more quickly and efficiently. Admittedly your car will get worse fuel efficiency when it runs cold, but it does not need to be at full operating temperature before you drive it.
      Wear and tear on your starter is not an issue unless you have a much older vehicle. Older cars that relied on carburetors did need to warm up more as they would not necessarily get the right fuel mixture at cold temperatures and were prone to stalling. This would require you to potentially start and restart your car putting extra wear on the started. In the 1980s the auto industry moved to electronic fuel injection, which eliminated this issue and warming up the car before driving became irrelevant.
      The key is that you need to idle long enough to circulate the oil in your engine, and that does not require 5, 10 or 15 minutes. Excessive idling can also be harmful for your engine as fuel is not fully combusted and the fuel residue can builds up on the cylinder walls and also contaminate the engine oil.
      The best option for you, your car, your pocket book, and the environment is to drive your car gently until all these components have an opportunity to start warming up. For more information on driving your car to warm it up you can visit http://greenactioncentre.ca/content/drive-to-warm-up-your-car/

    • bn880 | January 27, 2015 | 10:10 am | Reply

      You won’t wear out your starter when you RE-start your engine after it was off for 30-120 seconds. It’s an easy start that takes very little time on the starter provided that you have a properly functioning modern engine.

      • Dave Elmore | January 28, 2015 | 11:10 am | Reply

        Electronic ignition on today’s vehicles makes excessive wear on the starter from re-starting a thing of the past.

  12. Dave Fr | October 11, 2014 | 11:06 am | Reply

    To Mark Burch,
    Agreed that the road rage nowadays is pathetic and needs to change in Winnipeg

  13. Jane Seniw | October 8, 2014 | 1:35 pm | Reply

    After reading all the comments to date, I will throw a horse of a different colour into the mix-in reference to the health issues surrounding idling vehicles. On many occassions in our small town, trucks have sat idling-diesels are esp bad-as well as cars
    no apparent reason. The air is polluted soon after, my former neighbour and I actively persued the driver and requested that they turn off their rig/car. Even have called the trucking firms-if need be- explained the problem and most of them were not aware that their drivers were doing this. The truck/haul co’s changed their procedures.
    The air would be laden w/ fumes and particulate, esp bad in the winter. Call to Prov Health was of no help. Just somethings to ponder.

    • Dave Elmore | October 9, 2014 | 10:53 am | Reply

      All valid points. Especially true for larger trucks with diesel engines that they tend to just leave running.

    • Eric G | January 6, 2015 | 7:24 am | Reply

      Actually, truck drivers leave their truck running for a reason.. Diesel engines perform combustion with heat, rather than spark.. so instead of spark plugs of a gasoline engine, they have glowplugs that warm the air in the combustion chamber. If the air is too cold, the truck may not start at all or have a hard time getting hot enough to start.

      • Dave Elmore | January 7, 2015 | 3:19 pm | Reply

        Large trucks are a bit of a different situation although as you note the issue is “if the air is too cold.” Diesel engines do operate differently than gasoline engines however there is still no reason to idle unnecessarily. This is especially true for the many smaller diesel trucks and cars. People that own these vehicles do not need to operate on the same basis as big trucks.

  14. Benji | September 27, 2014 | 1:05 pm | Reply

    Cool to see citizen debate. In cold weather, “babying” your car until it warms up is better than idling for more than a minute, imho.

    The debate is wider than just “idle or not”. The debate extends to whether we want to have internal combustion engines, and what strategies we can use to mitigate their harmful effects in the short term.

    The best way to solve the idling debate is to get an electric car, because they cold-start with no extra wear and tear on the engine. #2 solution is to use a block heater on a timer to come on just before you start your car in the morning.

    • William Allan Ott | October 4, 2014 | 1:02 pm | Reply

      Yes, electric cars does solve the idling problem, but that is a very long way off. In the meantime, Americans have to be educated on how bad idling is for the environment and their engines. In Europe, they are educated on idling. In Switzerland, they have to shut off their engines at red lights. Everyone complies! They are serious about the environment. At railroad crossing throughout Europe, there are signs posted instructing motorists if the gates are down, they must shut off there engines.

      Approximately 3.8 million gallons of gasoline is gratuitously wasted from idling, daily throughout America. The oil companies are aware of this. The oil companies are paying off politicians and the DEP, not to educate the American people. They have stifled any kind of energy conservation programs here. Profits at the expense of our health and the environment! We must form a lobby/coalition to bring about change. “Strength in numbers.”
      http://www.idlingengines.blogspot.com

      • Dave Elmore | October 6, 2014 | 11:09 am | Reply

        We had a program called ecoDriver Manitoba a few years back which attempted to educate people in our province on fuel efficient driving and of course idling. Unfortunately funding was not renewed but the information that was developed was at least moved to our website. Thanks for your comments.

  15. Adam | September 26, 2014 | 8:37 pm | Reply

    Your numbers do not seem right to me. Anyone that drives in a large city with extensive traffic knows that idling uses very little fuel especially in newer cars. I go to the bonaroo festival every year in Tennessee and have sat waiting in line for over 14 hours in some cases and it has never used more than an eighth of a tank by your numbers I would have had to refuel multiple times to accomplish this I was also running the A/C since it was over 100 degrees outside. Know I certainly understand that the make model and year of the car could also be a major factor I drive a 2005 Toyota Camry.

    • Dave Elmore | September 27, 2014 | 10:14 am | Reply

      We obtained the values indicated from Natural Resources Canada’s website.
      http://www.nrcan.gc.ca/energy/efficiency/communities-infrastructure/transportation/idling/4397

      Under the section “Idling wastes fuel and money” it states:

      In fact, one of the most powerful arguments in favour of reduced idling is an economic one. For the average vehicle with a 3-litre engine, every 10 minutes of idling costs 300 millilitres (over 1 cup) in wasted fuel – and one half of a litre (over 2 cups) if your vehicle has a 5-litre engine. Unnecessary idling wastes fuel – and wasted fuel is wasted money.

      I also found research from the US that indicates “Idling probably wastes between 0.1 and 0.5 gal/hr for cars” at http://www.edf.org/sites/default/files/9236_Idling_Nowhere_2009.pdf

      While the numbers may not seem to be correct they are what research indicates.

      Thanks for your comments

    • James | October 18, 2014 | 11:34 am | Reply

      Response to Adam’s comment:
      You should probably check your own math. The range was 0.1 L to 0.4 L for 10 minutes of idling.
      0.1 x 6 = 0.6 L/hr.
      14 hours x 0.6 L/hr = 8.4 L.

      Even the smallest cars have tank capacities of 45 L or more, so we are actually talking about something in the neighbourhood of 1/8th of a tank.

      • Dave Elmore | October 19, 2014 | 11:47 am | Reply

        Guess I should have checked the math too. Thanks James for the clarification.

  16. Skyler Reinert | August 23, 2014 | 12:00 am | Reply

    For those of us that like to keep our vehicles for over 200,000 miles idling for only 30 seconds when it’s 0 degrees F outside definitely does more harm than good! Your engine internals are not properly lubricated until your engine oil is up to temp which happens just fine while idling. That’s why your engine has a thermostat built into the cooling system! Idling for 30 seconds and driving on down the road like normal puts undue stress on engine bearings and will most definitely wear out your engine prematurely.

    I can agree, however, that idling for extensive amounts of time does waste fuel but that’s a fee I’m willing to pay to stay cool when it’s sweltering hot outside or warm when my spit freezes before it hits the ground. There are far less emissions comin from your tailpipe when idling than the EPA leads you to believe.

    • Dave Elmore | August 24, 2014 | 3:34 pm | Reply

      We are not suggesting that you drive away after 30 seconds at your normal speed or acceleration. If the temperature is in fact very cold (-20 C or below) you may want to idle a bit longer which is why we say “On most days” you need no more than 30 seconds of idling before driving away. Even when it is very cold, idling until your engine is up to operating temperature is unnecessary. As we also indicate, “the other components” (transmission, wheel bearings etc) do not warm up while idling and will only warm while in motion. Until these components are warmed up your vehicle is not going to operate efficiently. Your engine as well will warm up “quicker and more efficiently” if you drive it. You can drive easy for a few minutes until the temperature gauge begins to rise and then drive normally.

      I agree that idling is in some respects a “fee” but an unnecessary fee in most cases and one that creates a great deal of CO2 emissions.

    • Jessica | September 6, 2014 | 1:05 pm | Reply

      You don’t drive away at regular speed after 30 seconds of idling when its -20. You start off slowly, getting out of your driveway. Then down the street at no more than 30 km until you get to the major road where you can then safely bring the car up to speed with harming your engine.

      Even then, every winter you should change your oil to 5d so it’s less viscous and less likely to freeze.

  17. Jackie | May 28, 2014 | 10:04 am | Reply

    I will say this, there are some circumstances where idling your car is necessary, such as when it is -40 degrees Celsius outside.

    • Dave Elmore | May 28, 2014 | 10:40 am | Reply

      There is some validity to your comment, however it is not necessary to idle your car for extended periods to warm it up, in fact it is not particularly good for your car. The other thing that wastes a lot of fuel is idling for extended periods while waiting for someone (school pick up is an example). While you don’t want to sit in the cold for extended periods either, but you can always cycle your car on and off to keep the chill at bay. The best way however is to simply plan your arrival so that you are not waiting.

      • Frank | June 4, 2014 | 2:04 pm | Reply

        I believe Jackie’s point was not to warm up her car, but to stay cool when the weather is too hot.

        • Dave Elmore | June 4, 2014 | 2:14 pm | Reply

          It did say -40 but either way, you can always cycle your air conditioning as well. I put it on air and then turn it off and when it gets warm I turn it back on.

  18. Naomi | March 2, 2011 | 2:35 pm | Reply

    In Germany, it is illegal to leave your vehicle idling while waiting at a train crossing. Is it possible to pass such a legislation in a country where we seem to value our own comfort above adding more carbon emissions to the world?

    • Macey T | March 2, 2014 | 4:00 pm | Reply

      so learned that in school the other day

    • Eunice | April 16, 2014 | 1:36 pm | Reply

      Thanks :)

  19. Mark Burch | February 25, 2011 | 1:54 pm | Reply

    I’m not sure why you’re “crowd sourcing” this sort of question, which, if framed a bit better, could probably best be answered by a faculty of automotive engineering at any of a dozen universities in North America that have them.

    Anyway, the “Is it better…?” part of your question implies a value judgment which you haven’t made explicit but which is crucial to answering the question, e.g., (a) better at reducing GHG emissions; (b) better at saving money; (c) better at reducing engine wear and by implication, vehicle life; (d) better at reducing fuel consumption; (e) better in terms of a life-cycle cost analysis which optimizes a, b, c, and d under conditions of idling versus stopping and restarting the engine. Real engineers might think of other relevant variables, e.g., perhaps ambient conditions like temperature and relative humidity also affect engine performance, etc. So to get an answer to the question, I think you need to start by clarifying the meaning of “better” in terms of which outcome(s)?

    Once the question is clear, the design for an empirical experiment would present itself and you could get data to answer the question.

    Based on my experience of driving in Winnipeg, however, I would suggest that the average latency period between a light turning green and the driver behind you laying on his/her horn is approximately 0.01 seconds—or less than the nerve transmission latency from the brain to the leg muscles needed to move your foot on the gas peddle. Adding perhaps as much as two full seconds to this delay which would be needed to restart your car will probably set off a city-wide cacophony of horn blowing and road rage. (Only kidding!)

    Good luck with your question.

  20. Michael Smith | February 25, 2011 | 9:41 am | Reply

    An often quoted guideline is if your car is going to be stopped for more than 10 seconds you are going to save gas overall by turning off the engine for that time and restarting it when you’re ready to go.

    As far as wear on engine components goes, yes there is more wear with turning off the ignition and restarting but this is more than offset by the fuel you will be saving by not idling.

    This is one of the ways in which a hybrid car saves on fuel consumption – by turning off the internal combustion engine whenever you are stopped or decelerating.

Newer Comments »

Continuing the Discussion

  1. Fuel Efficiency Tips for Truckers

    […] Registered charity, The Green Action Center indicates that every 10 minutes of idling costs up to four-tenths of a liter of fuel. Running the car while stopping uses fuel, without reason.

    October 23, 201511:52 pm
  2. Winter driving tips – Green Action Centre

    […] vehicle is to drive it. Idling in general wastes fuel and gets you nowhere. Check out our “Idling Wastes Fuel” myth busting […]

    January 6, 20142:21 pm

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