55mph cats

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.

Damn, This isn’t at ALL what I was hoping it would be about!

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.

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.

But if you don’t think I’m running out and starting a band called 55mph Cats, you’ve got another thing coming.


That was the intention. Couldn’t resist :smiley:

That’s provided you believe that anything to do with the oil industry can ever be “just a coincidence”…

[cue the conspiracy theorists]


I got caught out as well. :wink:

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?