[norraad]

The cat converters were put on as a concession to clean air as opposed to clean burn.

Clean burn would have reduced fuel use 20~30% over the past 50~60 years.

Meaning mideast monkeys would have 70~80% less money to buy weapons to cause trouble with, among other things.

This angle is hardly ever addressed.

Another angle is clean burn makes cars last longer, they hate that too.

As Lilly Tomlin says;

"No matter how cynical you become, it's never enough to keep up!"

[RightWhale]

That's true. There was a project engine back then by some amateurs working in the back yard under a shade tree who put some high performance parts on a stock engine. Things like a high flow polished intake manifold with a 4 barrel carb, high lift advanced spark cam, shaved heads, low constriction exhaust manifold, and got something like 30% increased gas mileage [with a light touch on the gas pedal] along with the expected power increase and of course lowered emissions.