Are those even user serviceable? So, it won't stop everyone but it will stop most of them.

Modern ICE cars have auto start/stop systems, so on a traffic light it has as much exhaust as an EV.

Oil in the exhaust in quantities high enough to produce acrid white smoke is extremely common on a number of ICE engines, like blown head gaskets on E25s (found in most Subarus before their Toyota involvement in 2010) for example

Probably. I read it as “had an impact but kept the performance stayed nominal.”

Yep. My newest car is over 20 years old. May be a bit more polluting (though it doesn't smell or smoke) but I've in theory saved the environmental impact of the manufacture of one or two new cars by keeping the old one.

I'm not spending $30-40k or more on a car. That just isn't going to happen.

I think expense is basically the problem.

Cost to replace the catalytic converter, cost for new exhaust pipes, cost to diagnose ignition timing problems. Whatever.

If the car drives and you don’t have the money I can completely understand why someone wouldn’t get the problem fixed. Even if it means they’re burning a 1/3 of their fuel, that’s still less in the short term than the $1500 it may cost to fix it.

It’s insanely rare I get the sense that the person is running really dirty on purpose.

I don’t know what a realistic fairway to fix it is. They’re probably isn’t one. I don’t think fines would work, it would probably just make things worse. Seems like the kind of thing where a little government group to find the worst 0.1% of cars on the road and just get them back to reasonable levels would be a huge help.

But that’s not how we do things.

Incomplete combustion will ruin a cat. That's not its purpose, it's there to reduce NOx emissions.

> A lot of Americans take their cat off on purpose for louder noises.

Some people remove catalytic converters when they install a performance exhaust. Nobody is doing it for louder noises because the muffler portion is what dampens the sound.

Also I wouldn’t say it’s “a lot of Americans”. We have emissions inspections in most major cities and your car won’t pass if you remove the catalytic converter. They can now detect modified ECUs, too. Someone would have to be so determined to do this that they’d swap the exhaust in and out every time they had to do emissions inspections.

I’ve run into a few of those. They’re generally pretty obvious. Usually a big truck, lots of MAGA & adjacent bumper stickers.

I haven’t noticed people removing the catalytic converters just for noise. The rare time I see a car that wants to be loud it usually just seems to be the exhaust end they changed, or maybe removed the muffler.

The kind of stuff I’m complaining about mostly seems to be older cars, or those in poor mechanical shape. Cases where the people probably just don’t have the money to fix it.