# How do they decide which side of the car to put the gas cap on? **URL:** \ **Category:** Factual Questions\ **Created:** [July 30, 2003, 4:48am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837 "2003-07-30T04:48:09Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Gumbercules](https://avatars.discourse-cdn.com/v4/letter/g/a183cd/32.png) [@Gumbercules](https://boards.straightdope.com/u/Gumbercules)\ **Post date:** [July 30, 2003, 4:48am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/1 "2003-07-30T04:48:09Z")
Pardon my grammar. The title says it all. Aslo, whatever happened to the gas cap behind the license plate? ---
**Author:** ![Gunslinger](https://avatars.discourse-cdn.com/v4/letter/g/4491bb/32.png) [@Gunslinger](https://boards.straightdope.com/u/Gunslinger)\ **Post date:** [July 30, 2003, 5:01am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/2 "2003-07-30T05:01:50Z")
WAG: Whim of the designer, most likely. Behind-the-plate: In my experience owning a car with this setup, it’s rather inconvenient. Because the filler pipe is almost flat, the gas tends to back up in the pipe and pop the pump’s auto-shutoff mechanism before the tank is anywhere near full. Also, if the car is low to the ground at all, you have to pretty much squat/get down on your knees to reach it. With the filler hole high on the fender, you can stand up straight, and the gas falls into the tank without backing up in the pipe. It is nice not having to worry about getting on a certain side of the pumps, though. ---
**Author:** ![kniz](https://avatars.discourse-cdn.com/v4/letter/k/c37758/32.png) [@kniz](https://boards.straightdope.com/u/kniz)\ **Post date:** [July 30, 2003, 5:10am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/3 "2003-07-30T05:10:47Z")
There is a guy locked in a room somewhere in the Detroit area. The automobile companies pay money for his services. Their representatives knock on his door. He calls out either “right” or “left” and every once in awhile “middle”. He has never divulged his secret concerning how he knows exactly which side the gas cap should be on. Some people think it is an talent one is born with. :rolleyes: ---
**Author:** ![SlickRoenick](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@SlickRoenick](https://boards.straightdope.com/u/SlickRoenick)\ **Post date:** [July 30, 2003, 6:25am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/4 "2003-07-30T06:25:40Z")
I tend to see most modern cars have the gas cap opposite of the muffler, at least, that’s the pattern I’ve noticed. Trucks though are (again, in my umm, what’s the word? noticements?) have caps on the same side as mufflers. YMMV ---
**Author:** ![Mudshark](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@Mudshark](https://boards.straightdope.com/u/Mudshark)\ **Post date:** [July 30, 2003, 7:23am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/5 "2003-07-30T07:23:00Z")
I like my behind the license plate gas tank. Although, I have to be sure I pull up far enough so the pump reaches. I think they put it on the driver’s side so it is easier for the driver to pull up and pump the gas. It also means the cord on the pump doesn’t have to be as long. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [July 30, 2003, 7:27am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/6 "2003-07-30T07:27:25Z")
I’ve filled one plate-filled car - the hose only just reached, and it overflowed when it was full. Good riddance! ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 30, 2003, 10:17am UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/7 "2003-07-30T10:17:30Z")
We’ve done this thread a couple of times. Highlights: there’s no real logic to the placement, and has nothing to do with the exhaust. It mostly has to do with (1) where it will fit, (2) where the filler neck is on current and previous models coming off the same line; and (3) the shape and location of the tank in the vehicle. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [July 30, 2003, 12:17pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/8 "2003-07-30T12:17:45Z")
I believe the behind-the-plate gas filler was removed due to safety concerns in rear end collisions. ---
**Author:** ![BwanaBob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bwanabob/32/2985_2.png) [@BwanaBob](https://boards.straightdope.com/u/BwanaBob)\ **Post date:** [July 30, 2003, 12:17pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/9 "2003-07-30T12:17:58Z")
Hmmm. I always thought the cap was on the side of the driver. The only exceptions being if the car was designed in a country where the steering wheel was on the “other” side and the car was retooled for the other country. Ex. My old Probe was designed in the US and the cap was on the left; my Subaru Forester was designed in Japan hence the cap is on the right. I know that “two” doesn’t cut it for statistics, but I just made that assumption. Am I wrong? As a nicety, the instrument panel in the Forester has a little icon of a gas pump with an arrow pointing to the right; just to remind me. ---
**Author:** ![dead0man](https://avatars.discourse-cdn.com/v4/letter/d/edb3f5/32.png) [@dead0man](https://boards.straightdope.com/u/dead0man)\ **Post date:** [July 30, 2003, 12:38pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/10 "2003-07-30T12:38:13Z")
My VW would tend to disagree with you. Its gas cap is on the right side you see. Also, my last Subaru had it on the left side. ---
**Author:** ![BwanaBob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bwanabob/32/2985_2.png) [@BwanaBob](https://boards.straightdope.com/u/BwanaBob)\ **Post date:** [July 30, 2003, 12:55pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/11 "2003-07-30T12:55:02Z")
Oh well; another theory shot to hell. Thanks for the info. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 30, 2003, 1:14pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/12 "2003-07-30T13:14:01Z")
My designed and assembled in USA GM vehicle had a left-side filler neck. The designed and assembled in USA Ford Co. vehicle has a right-side filler neck. Both are pure Detroit iron; no overseas influence. Both are dual tailpipes. ---
**Author:** ![refusal](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@refusal](https://boards.straightdope.com/u/refusal)\ **Post date:** [July 30, 2003, 1:21pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/13 "2003-07-30T13:21:24Z")
> [@](#): > > \*Originally posted by kniz \* > \*\*There is a guy locked in a room somewhere in the Detroit area. The automobile companies pay money for his services. Their representatives knock on his door. He calls out either “right” or “left” and every once in awhile “middle”. He has never divulged his secret concerning how he knows exactly which side the gas cap should be on. Some people think it is an talent one is born with. :rolleyes: \*\* By ensuring a random distribution of gas caps on either side, he enables filling stations to put the pumps back to back, allowing increased profits for the oil companies, better service for the motorist, and happiness all round. Uniformity would be disasterous. Or maybe I’m talking crap. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 30, 2003, 1:48pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/14 "2003-07-30T13:48:18Z")
My Ford Taurus has the filler on the right side. My Ford Windstar (built on a Taurus platform) has the filler on the left side. Go figure. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [July 30, 2003, 2:04pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/15 "2003-07-30T14:04:02Z")
Back in the early 60’s, my mom had a car which actually had the fuel cap behind a taillight! One manually rotated the taillight by 90 degrees to reveal it, unscrewed the cap, and filled it up. We took great joy in causing much consternation among gas station attendants. Now, can anyone tell me what kind of car that might have been? I was a wee tyke then, and can’t recall. Mom and Dad are no longer available to enlighten me. ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [July 30, 2003, 2:43pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/16 "2003-07-30T14:43:27Z")
Murphys Law of petrol stations: the gas cap is always on the opposite side to the only free pump. ---
**Author:** ![badmana](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@badmana](https://boards.straightdope.com/u/badmana)\ **Post date:** [July 30, 2003, 2:55pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/17 "2003-07-30T14:55:14Z")
Lets see, just a slight poll on my cars. The 88 Bonneville had it on the right (passenger side). The 92 Voyager on the left. My new Matrix on the left. I always though american cars were more prone to keeping the filler on the right for safety purposes (for filling up on the side of a road) but this isn’t the experience I had with my cars. And my Matrix’s filler is on the side of the muffler/tailpipe. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [July 30, 2003, 3:11pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/18 "2003-07-30T15:11:20Z")
> [@](#): > > \*Originally posted by Qadgop the Mercotan \* > \*\*Back in the early 60’s, my mom had a car which actually had the fuel cap behind a taillight! One manually rotated the taillight by 90 degrees to reveal it, unscrewed the cap, and filled it up. We took great joy in causing much consternation among gas station attendants. > > Now, can anyone tell me what kind of car that might have been? I was a wee tyke then, and can’t recall. Mom and Dad are no longer available to enlighten me. \*\* I think more than one maker did it, but this guy gives it as an identifying feature for the '56 Chevy (not the 55 or 57): [http://www.chevytrucks.org/marvinsgarage/carrecognition.html](http://www.chevytrucks.org/marvinsgarage/carrecognition.html) ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 30, 2003, 3:12pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/19 "2003-07-30T15:12:16Z")
Seems I’ve found two competing standards within one company: > [@](#): > > **The fuel system shall be packaged on the side of the underbody opposite to where the exhaust system is routed to facilitate meeting [our requirement]. This includes the placement of the fuel filler pipe and its inlet and the fuel line routing. If the fuel tank cannot be packaged in one side of the vehicle it is acceptable for it to extend across the vehicle.** and > [@](#): > > **If the requirements of [something] can met, the preferred location for the fuel fill inlet (fuel filler pipe, housing and door) is on the left side of the vehicle on each platform. > RATIONALE: Our customers and our assembly plants prefer that the filler pipe opening be consistently on the same side of the vehicle on all [company] products. Of those that have a preference, most prefer the filler opening on the left. The [requirement] only requires the filler opening to be on the side of the vehicle (i.e., front, back and top are excluded).** ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [July 30, 2003, 3:13pm UTC](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837/20 "2003-07-30T15:13:53Z")
Truck gas tanks should be in the middle for safety. Safety & engineering determines which side of the gas tank the cap is on & since no two cars have the same design, no two have the cap in the same location. Let’s not forget the Ford Pinto 🙂 [Next page](https://boards.straightdope.com/t/how-do-they-decide-which-side-of-the-car-to-put-the-gas-cap-on/191837.md?page=2)