One thing the news mention to fail is how it is to breath that. Never been to places that bad but other big cities in Eastern Europe or Asia with a small fraction of what Beijing has you have a constant sore nose sensation, similar to a sore throat except is mostly the nose and back of the mouth. When you blow your nose your boogers are black... Not pleasant, maybe I was a visitor and was not toughened up like the locals but I am sure they feel it too.
There is also a ton of cars on the road that you can barely see through the smoke they make. Clean cars are available, just that not all people afford to get them. Gas/Diesel is not as clean either at all pumps. And the worst are actually the big trucks, delivery trucks or "workhorse" cars.
We have it good here in North America and i think it has to do with the laws being enforced. At the same time I am sure some performance parts can be allowed, maybe one should pay a bit more for that, again with some limits. I love cars and raw exhausts but I do not want everybody to drive them

As I type I remember the sore throat polluted air gives you and it is not fun.
And to be honest unmaintained cars are the worst, burning oil or improperly burning gas, not the random relatively rare performance exhaust car.
Classic cars are allowed on the road even if they do not pass emission testing, not sure about California, and I am sure there is an extra cost involved in that. So solutions exist and I bet not everybody will pay so it can work out.
And one huge thing few people mention is that pollution is usually industrial, commercial transport and not so much avergae joes going to work. Same like Earth Day when people turn off lights in the city "for show" or awareness, but in the end industrial consumption and industrial pollution is the one driving this, yet nobody drives awareness programs on that for some reason. And industrial also means the huge manufacturing beast that is China.
I am passionate about cars and I always get annoyed when cars are portrayed as the evil of pollution when in reality it is way more than just cars. Buying stuff made in China may be more polluting than going to work in our 2.4 "gas guzzlers"

Personally i try to buy local products even if a bit pricier, it also gives jobs to people around me which is good since I am one of them, even if an "import" so to speak.
Sorry for the long rant, somehow I typed too much, I do not mean to preach or convince anybody, I am not sure myself what the solution is for all this
