# turning the car off when you pump gas **URL:** \ **Category:** Factual Questions\ **Created:** [March 12, 2012, 1:04am UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505 "2012-03-12T01:04:41Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 12, 2012, 11:57am UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/21 "2012-03-12T11:57:20Z")
> [@Rick](#): > > The problem occurs when you have a plastic gas can. Static builds up from the fuel flowing into the can. If the can is on the ground the charge disapates. However if you leave the can in the bed that has a bed liner the can is insulated. When you remove the nozzle A spark can jump and ignite the vapors. > I saw this happen at Willow Springs Raceway once. Seems like this sort of thing pops up on the local news once a year or so: gas station surveillance cameras catch somebody filling up a gas can on the bed of a pickup truck, and suddenly there’s a fire. In the best outcome, just the truck burns; in the worst outcome, the victim flings the hose and/or tips the gas can and gets fuel on himself, resulting in serious burns. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [March 12, 2012, 12:26pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/22 "2012-03-12T12:26:34Z")
> [@beowulff](#): > > He said “electrical problem with the car” - static discharge can occur whether the car is running or not. Fires from sparks caused by static buildup have been mistakenly interpreted as fires caused by cell phones. ---
**Author:** ![Corcaigh](https://avatars.discourse-cdn.com/v4/letter/c/eb8c5e/32.png) [@Corcaigh](https://boards.straightdope.com/u/Corcaigh)\ **Post date:** [March 12, 2012, 1:51pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/23 "2012-03-12T13:51:17Z")
> [@Dog80](#): > > My car (Peugeot 207) has a locking cap that opens with the car key. So you have to turn the car off to release the key and then go out and unlock the cap. > > Once the cap is opened, the key gets stuck there so you can’t use it until you put the cap back in place and lock it again. I had the same make (different model) car for over a decade, it’s just become a habit to me to turn the engine off when I fill 'er up. Previously to that my father had a large saloon that had a lockable flap over the petrol cap, so I grew up with people switching off the engine when they filled up. I was told it was to do with preventing a fire, caused by a spark igniting the fumes - if the engine is running it supposedly causes a bigger fire/explosion. I’ve only ever met one person who leaves the engine running when they fill up ---
**Author:** ![anson2995](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@anson2995](https://boards.straightdope.com/u/anson2995)\ **Post date:** [March 12, 2012, 1:57pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/24 "2012-03-12T13:57:25Z")
We’ve [discussed this](http://boards.straightdope.com/sdmb/showthread.php?t=320596) here [several times](http://boards.straightdope.com/sdmb/showthread.php?t=259221), and the consensus has been that there’s no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling. I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example. The risk of the car jumping into gear is almost entirely an issue of operator error, and nearly impossible with an automatic transmission. **aceplace57** points to an industry report from 1980. it’s worth pointing out that this was more than 30 years ago, and very few of those cars are still on the road. The number of cars and light trucks with manual transmission has dropped from about 40% to 5% since then. ---
**Author:** ![tullsterx](https://avatars.discourse-cdn.com/v4/letter/t/e9bcb4/32.png) [@tullsterx](https://boards.straightdope.com/u/tullsterx)\ **Post date:** [March 12, 2012, 2:01pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/25 "2012-03-12T14:01:08Z")
What is the rational for leaving it running? I can’t think of any good reason. ---
**Author:** ![Gedd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gedd/32/4938_2.png) [@Gedd](https://boards.straightdope.com/u/Gedd)\ **Post date:** [March 12, 2012, 3:10pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/26 "2012-03-12T15:10:32Z")
> [@tullsterx](#): > > What is the rational for leaving it running? I can’t think of any good reason. Heat? Sitting in the car while it’s filling up (which I believe is a major factor in fires at the pump). Making a quick getaway? Umm . . . wasting gas? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [March 12, 2012, 3:30pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/27 "2012-03-12T15:30:25Z")
How do you sit in the car while the pump is running? Don’t all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [March 12, 2012, 3:34pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/28 "2012-03-12T15:34:10Z")
Young kids fall asleep in the car pretty easily. When i pull into a gas station and my daughter is asleep and it’s 90 degrees outside, I leave it running ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [March 12, 2012, 3:44pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/29 "2012-03-12T15:44:16Z")
> [@Leaffan](#): > > How do you sit in the car while the pump is running? Don’t all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here. Where is here? In California most of the pumps have a little catch you can flip down so you don’t have to hold the pump while it is filling. I seem to recall the same thing being true in Utah, Colorado, Arizona and New Mexico. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 12, 2012, 3:46pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/30 "2012-03-12T15:46:36Z")
> [@anson2995](#): > > We’ve [discussed this](http://boards.straightdope.com/sdmb/showthread.php?t=320596) here [several times](http://boards.straightdope.com/sdmb/showthread.php?t=259221), and the consensus has been that there’s no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling. > > I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example. > > The risk of the car jumping into gear is almost entirely an issue of operator error, and nearly impossible with an automatic transmission. **aceplace57** points to an industry report from 1980. it’s worth pointing out that this was more than 30 years ago, and very few of those cars are still on the road. The number of cars and light trucks with manual transmission has dropped from about 40% to 5% since then. I had to rescue my next-door neighbor when she got out of her car before turning it off (or putting it in park). The car lurched forward, and she got caught in the seatbelt and dragged. She was extremely lucky that she didn’t get her legs crushed. So, I can see that if someone gets out of the habit of turning the car off, then they increase their chances of leaving the car in gear and running when they pull up to the gas pump, with the predictable consequences. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 12, 2012, 3:47pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/31 "2012-03-12T15:47:20Z")
Long ago in a galaxy far, far away, the chances of a “runner” were much more than today. Back then it was possible to fuel your vehicle and then take off without paying. I knew one self-serve station manager that always kept a quart of oil (paper can) on top of one of the pumps. I asked him why it was there, and doesn’t he risk getting it stolen. Yes, there was always a risk someone would steal it, but the cost of a quart of oil was less than the cost of a runner with a tank of gas. Seems the station manager had a pretty good throwing arm so if he had a runner, he would lob that quart of oil at the fleeing vehicle. It made it easier for the police to track down the vehicle. During the winter, the can of oil was a bit “harder” than summer. More often than not the can would go through the rear window before breaking up. 😃 ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [March 12, 2012, 4:08pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/32 "2012-03-12T16:08:10Z")
> [@gazpacho](#): > > Where is here? In California most of the pumps have a little catch you can flip down so you don’t have to hold the pump while it is filling. I seem to recall the same thing being true in Utah, Colorado, Arizona and New Mexico. Here is Ontario, Canada. The catches are all removed so that you can’t walk away from a running pump. (You could perhaps stick the gas cap or something in there I suppose.) ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [March 12, 2012, 4:30pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/33 "2012-03-12T16:30:09Z")
> [@Leaffan](#): > > (You could perhaps stick the gas cap or something in there I suppose.) And a lot of idiots do. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 12, 2012, 4:34pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/34 "2012-03-12T16:34:25Z")
> [@tullsterx](#): > > What is the rational for leaving it running? I can’t think of any good reason. car full of people in 100+ weather. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [March 12, 2012, 4:53pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/35 "2012-03-12T16:53:42Z")
> [@Leaffan](#): > > How do you sit in the car while the pump is running? Don’t all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here. Not in the US- some gas station operators remove them (or they break), most don’t. The pumps here all have automatic shutoffs, though; I assume they do in Canada too. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [March 12, 2012, 5:03pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/36 "2012-03-12T17:03:59Z")
> [@Really\_Not\_All\_That\_Bright](#): > > Not in the US- some gas station operators remove them (or they break), most don’t. The pumps here all have automatic shutoffs, though; I assume they do in Canada too. Yep. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [March 12, 2012, 5:09pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/37 "2012-03-12T17:09:48Z")
> [@pullin](#): > > Is it the bedliner that isolates the gas can? I’ve never really understood this one. I figured that the metal-to-metal contact when you insert the nozzle in your car’s fuel tank zeroes out any building charge, and that what is missing when filling a fuel tank in an ungrounded car. > > I once got a lecture about this from a well-meaning individual while filling a bunch of gas cans in my pickup bed (I didn’t want to lift them all back in). I silenced him by pointing out that I had grounded the bed itself with a large piece of angle-iron running to the asphalt. I have no idea whether that would work, or whether I need to ground to the pump, like they do with airplanes. The bedliner does isolate the gas can, so the cans can have a charge differential with respect to the rest of the truck or with the pump, allowing a spark to occur. You could still have a charge differential with respect to yourself/the pump/the truck/gas cans even if you have metal cans sitting in contact with a metal bed. The semi-enclosed bed of a truck also tends to catch fumes that would otherwise blow away in the wind, increasing the risk. The angle-iron on would ground any charge on the truck. A direct connect to the pump would make a better ground. In either case, you still have the issue where the charge may be built up on you and not on the vehicle (typical of a person sliding across the seat in the winter, for example). I suppose you could be absolutely anal about it and attach a ground strap to your wrist and the pump as well. A more practical solution is just to touch something metal on the truck somewhere away from where the fuel vapors might be to equalize the charge between the truck and yourself. > [@anson2995](#): > > We’ve [discussed this](http://boards.straightdope.com/sdmb/showthread.php?t=320596) here [several times](http://boards.straightdope.com/sdmb/showthread.php?t=259221), and the consensus has been that there’s no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling. Keeping the engine running keeps charge building up, mostly due to the moving belts. Otherwise, any charge built up would dissipate through the vehicle’s tires. So there is a slightly higher risk with leaving the engine running. In order to have a fire, you need fuel, oxygen, and a source of ignition. When you pull into the gas station, you generally don’t have fuel vapors just hanging about, so there’s no fuel source. If you don’t keep the engine running, any charge built up on the vehicle from the engine or just from the vehicle moving through the air will dissipate quickly, removing your potential source for ignition. So in that respect it is more dangerous to leave the vehicle running than it is just to pull into the station. > [@anson2995](#): > > I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example. There are two examples in the PEI report (I just checked - you can get to it from Rick’s link upthread) where they note that the vehicle had been left running. It’s not clear from the circumstances though if the running engine actually had anything to do with the static discharge. In both cases the driver got in and out of the car as well, which may have generated the static charge. ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [March 12, 2012, 5:22pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/38 "2012-03-12T17:22:39Z")
I always turn off the engine, not just because the sign on the pump says so, but because I see no reason to waste gas. Even if it’s 100 degrees, 5 minutes of no AC isn’t going to kill anyone. Why, back in MY day, nobody had an air-conditioned car. \ Dam kids these days and their fancy air-conditioned cars… ---
**Author:** ![JoshuaSD](https://avatars.discourse-cdn.com/v4/letter/j/f1d935/32.png) [@JoshuaSD](https://boards.straightdope.com/u/JoshuaSD)\ **Post date:** [March 12, 2012, 6:05pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/39 "2012-03-12T18:05:04Z")
My two cents: It takes only a few minutes to fill the tank on a car. (Maybe 10 minutes for a big truck?) When our statement is that we have kids in the car so we are leaving it running to protect them from the heat/cold I cant buy that. The car does not heat up that fast even in the hot summer sun. Google “child knocks car into drive” and the results should convince anyone that this is a very bad idea. Add to the problem of the car careening through the gas station window that the pump being torn out may have sprayed you with flammable fuel and rescue is now even more hampered. One spark from a car half way through a store window is not that unlikely. Again just an opinion. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 12, 2012, 6:17pm UTC](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505/40 "2012-03-12T18:17:26Z")
> [@Really\_Not\_All\_That\_Bright](#): > > Not in the US- some gas station operators remove them (or they break), most don’t. The pumps here all have automatic shutoffs, though; I assume they do in Canada too. The automatic shutoffs are not 100% reliable. A couple of weeks ago I was pumping gas and left the nozzle unattended while I cleaned the rear window of my car. I started hearing splashing noises and immediately realized my tank was full and the dispenser was still pumping gas; I ended up with maybe a quart of gas on the ground before I got it stopped. Getting gas? Shut your car off, and don’t get too far from the nozzle. Definitely don’t get back into your car; not only can this generate static electricity, but you may not be able to respond in a timely manner if the automatic shutoff doesn’t work. Your cell phone won’t start a fire, but you probably should give your full attention to what you’re doing while you refuel your vehicle; make/take the call after you’re done. [Previous page](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505.md?page=1) [Next page](https://boards.straightdope.com/t/turning-the-car-off-when-you-pump-gas/615505.md?page=3)