# Car gas cap question **URL:** \ **Category:** Factual Questions\ **Created:** [July 19, 2004, 10:28pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887 "2004-07-19T22:28:19Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [July 19, 2004, 10:28pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/1 "2004-07-19T22:28:19Z")
Why do some cars have the gas cap on the driver’s side, while others have it on the passenger side? I recently got a new car, and I’m still getting used to filling up on the driver’s side. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [July 19, 2004, 11:18pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/2 "2004-07-19T23:18:25Z")
Because the design engineers don’t care what side it’s on. In fitting exhaust, brake lines, suspension pieces, etc., they just need to come up with a package that works as a whole. Exhaust pipe routing probably has the most effect on fuel tank and fuel filler/gas cap placement, and some engine configurations are better served by having exhaust pipes on one particular side. ---
**Author:** ![iwakura43](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@iwakura43](https://boards.straightdope.com/u/iwakura43)\ **Post date:** [July 19, 2004, 11:44pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/3 "2004-07-19T23:44:25Z")
A recent Car Talk puzzler taught me that if a car has tailpipes on only one side, then the gas cap is invariably on the other side. I’ve started noticing this whenever I’m at the gas station, and I have yet to find a counterexample. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [July 20, 2004, 1:21am UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/4 "2004-07-20T01:21:00Z")
> [@Gary T](#): > > Because the design engineers don’t care what side it’s on. In fitting exhaust, brake lines, suspension pieces, etc., they just need to come up with a package that works as a whole. Exhaust pipe routing probably has the most effect on fuel tank and fuel filler/gas cap placement, and some engine configurations are better served by having exhaust pipes on one particular side. GaryT: I’ve learned to respect your Automotive Knowledge. Thanks for your input. One hijack: How close can an ehxaust pipe be to the fuel tank? ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [July 20, 2004, 5:49am UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/5 "2004-07-20T05:49:46Z")
in the old days within a few inches. Nowadays, the further the better. Fire? No. Emissions. The colder the fuel in the tank, the less of a load on the evaporative system. so by keeping the exhaust away from the tank, the fuel is kept cooler. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [July 20, 2004, 5:53am UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/6 "2004-07-20T05:53:10Z")
> [@iwakura43](#): > > A recent Car Talk puzzler taught me that if a car has tailpipes on only one side, then the gas cap is invariably on the other side. I’ve started noticing this whenever I’m at the gas station, and I have yet to find a counterexample. Buzzzzzst! Wrong, but thank you for playing 1998-2000 Volvo V70 AWD Exhaust ran down the middle of the car, tailpipe outlet was on the passenger side, and the fuel tank filler was also on the passenger side. Car talk is entertainment, not always factual. ---
**Author:** ![SlickRoenick](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@SlickRoenick](https://boards.straightdope.com/u/SlickRoenick)\ **Post date:** [July 20, 2004, 11:45am UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/7 "2004-07-20T11:45:51Z")
> [@iwakura43](#): > > A recent Car Talk puzzler taught me that if a car has tailpipes on only one side, then the gas cap is invariably on the other side. I’ve started noticing this whenever I’m at the gas station, and I have yet to find a counterexample. I had noticed that myself years ago and believed it, but there are many many pickup trucks that have cap and exhaust on the same side. ---
**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 20, 2004, 1:15pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/8 "2004-07-20T13:15:26Z")
> [@Rick](#): > > Buzzzzzst! Wrong, but thank you for playing > 1998-2000 Volvo V70 AWD > Exhaust ran down the middle of the car, tailpipe outlet was on the passenger side, and the fuel tank filler was also on the passenger side. > > Car talk is entertainment, not always factual. In the original Car Talk segment, they said it was roughly 95% accurate, and they were right. There are exceptions, like your Volvo, but they are rare. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [July 20, 2004, 3:57pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/9 "2004-07-20T15:57:48Z")
> [@Telemark](#): > > In the original Car Talk segment, they said it was roughly 95% accurate, and they were right. There are exceptions, like your Volvo, but they are rare. Trust me, there are plenty of others, the AWD Volvo is just the one that bubbled to the top of my mind first. ---
**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 20, 2004, 5:41pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/10 "2004-07-20T17:41:06Z")
Here are a few other threads where this was discussed. Seems we never reached any definitive conclusions. [201125](http://boards.straightdope.com/sdmb/showthread.php?t=201125) [161218](http://boards.straightdope.com/sdmb/showthread.php?t=161218) [133340](http://boards.straightdope.com/sdmb/showthread.php?t=133340) ---
**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 20, 2004, 6:16pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/11 "2004-07-20T18:16:01Z")
> [@Rick](#): > > Trust me, there are plenty of others, the AWD Volvo is just the one that bubbled to the top of my mind first. I have not doubt that there are others. But based on the number of cars on the road, and purely anecdotal evidence, I’d say the percentage numbers are very accurate. I grant you that I have no empirical evidence, but so far none has been presented in this thread. My rough guess is that for every 1 Volvo AWD there are dozens of Camrys, Accords, and Tauruses to make the numbers add up. ---
**Author:** ![jdc](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jdc](https://boards.straightdope.com/u/jdc)\ **Post date:** [July 20, 2004, 6:21pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/12 "2004-07-20T18:21:25Z")
I’d almost switch from Hertz to the first rental car company that would take the time to post a little sticker with an arrow on the dash on all their cars: \<== Fuel Fill This Side or Fuel Fill This Side ==\> Sometimes the auto manufacturer puts that on the instrument panel, but only some do this. ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [July 20, 2004, 6:32pm UTC](https://boards.straightdope.com/t/car-gas-cap-question/255887/13 "2004-07-20T18:32:11Z")
My 1990 Acura Integra has the tailpipes and gas fill on the drivers side.