# 55mph cats **URL:** \ **Category:** Factual Questions\ **Created:** [February 20, 2001, 3:29pm UTC](https://boards.straightdope.com/t/55mph-cats/55216 "2001-02-20T15:29:46Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [February 20, 2001, 3:29pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/1 "2001-02-20T15:29:46Z")
Over on Great Debates they’re discussing the removal of the 55mph speed limit if an American state doesn’t want it. Apparantly the 55mph speed limit was there to conserve energy with the save lives reason put there to make it more palpable. But what I want to know is whether or not 55mph was chosen to preserve early catalytic converters that worked best at this speed or is this just an urban legend. ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [February 20, 2001, 4:40pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/2 "2001-02-20T16:40:10Z")
Damn, This isn’t at ALL what I was hoping it would be about! ---
**Author:** ![Shiva](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@Shiva](https://boards.straightdope.com/u/Shiva)\ **Post date:** [February 20, 2001, 4:40pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/3 "2001-02-20T16:40:23Z")
I can’t imagine how the speed of the car would affect the functioning of it’s catalytic converter. What would affect the converter is the amount of exhaust gas passing through it. Engine RPM would be the determining factor here, not vehicle speed. Driving around town at 35 MPH in second gear could easily produce more exhaust than loping down the highway in overdrive. ---
**Author:** ![bizerta](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@bizerta](https://boards.straightdope.com/u/bizerta)\ **Post date:** [February 20, 2001, 6:16pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/4 "2001-02-20T18:16:51Z")
IIRC, catalytic converters first appeared on 1974 automobiles, which appeared in the late summer of 1973. Congress had demanded that new cars emit less polutants and CC’s did it. The Arab oil embargo which occurred a bit later (November?) was the driving force to the 55 MPH speed limit. It’s just a coincidence that the two events occurred nearly simultaneously. ---
**Author:** ![tiny\_ham](https://avatars.discourse-cdn.com/v4/letter/t/a183cd/32.png) [@tiny\_ham](https://boards.straightdope.com/u/tiny_ham)\ **Post date:** [February 20, 2001, 7:04pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/5 "2001-02-20T19:04:31Z")
> [@](#): > > \*Originally posted by Sigene \* > Damn, This isn’t at ALL what I was hoping it would be about! But if you don’t think I’m running out and starting a band called 55mph Cats, you’ve got another thing coming. jarbaby ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [February 21, 2001, 12:32pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/6 "2001-02-21T12:32:56Z")
> [@](#): > > \*Originally posted by Sigene \* > \*\*Damn, This isn’t at ALL what I was hoping it would be about! \*\* That was the intention. Couldn’t resist 😃 ---
**Author:** ![Duck\_Duck\_Goose](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)\ **Post date:** [February 21, 2001, 2:12pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/7 "2001-02-21T14:12:09Z")
> [@](#): > > \*Originally posted by bizerta \* > \*\*IIRC, catalytic converters first appeared on 1974 automobiles, which appeared in the late summer of 1973. Congress had demanded that new cars emit less polutants and CC’s did it. The Arab oil embargo which occurred a bit later (November?) was the driving force to the 55 MPH speed limit. It’s just a coincidence that the two events occurred nearly simultaneously. \*\* That’s provided you believe that anything to do with the oil industry can ever _be_ “just a coincidence”… [cue the conspiracy theorists] 😃 ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [February 23, 2001, 1:14pm UTC](https://boards.straightdope.com/t/55mph-cats/55216/8 "2001-02-23T13:14:28Z")
> [@](#): > > \*Originally posted by Sigene \* > \*\*Damn, This isn’t at ALL what I was hoping it would be about! \*\* I got caught out as well. 😉 A long train of thought ensued. I thought about terminal velocity, I thought about highrise buildings, large aggressive dogs, and cats’ legendary ability to remain upright. In the end, all this garbage circulating in my brain came down to one clear realisation: Isn’t the word “meow” just the most perfect word in the English language for describing the doppler effect. Coincidence, no?