Thoughts about CO2, CATs, & gasoline fuel economy

[oil pan 4]

If you don't have a smog problem where you live and if a 3 way cat costs more, why bother?

[Hersbird]

Originally Posted by oil pan 4

I don't think catalytic converters effect car fuel economy at all or barely at all.
After driving my electric so much I think fuel burners all stink. If you want to reduce back pressure removing the muffler and running just a converter would be better.

I would agree but only when the car is designed to run a cat. What if because you didn't have to worry about heating up a cat you could run completely different A/F ratios? Run different timing and compression then designed for the lean burn too. I think there are a bunch of non-starters in potential economy boosters because of that rich fuel mixture the cat needs.

[oil pan 4]

I have ran lean burn through a cat.
You actually get more HC when you run a little lean.
Regular exhaust heat rejection will easily keep the catalyst hot enough to decompose left over HC with the abundance of oxygen. It won't do it with in 15 or 30 seconds of start up like a modern engine that runs balanced A/F but after a few minutes it will achieve decomposition.