Modern cars minimize soot mostly by carefully controlling the combustion to produce a minimum of it. Any unburned fuel is an inefficiency, reducing gas mileage. Computer-controlled fuel injection helped advance this a lot (over carburetion).
So…cars don’t “filter soot”?
Most cars using a diesel engine are indeed fitted with a particulate filter nowadays. It is more or less necessary to meet environmental standards in most of the world. So at least some cars do.
Cars with modern fuel-injected engines produce very little particulate exhaust, and what little they do produce is burned in the catalytic converter.
What about gas cars that are a majority?
Poorly. Particulate filters have been common on passenger car diesels since the 80s.
So the vast majority of passenger vehicles (diesel is very small %)…don’t filter soot? Not sure what GP said was accurate then.
The vast majority do, certainly anything from the past decade or so does because it would be impossible to meet the pollution standards otherwise. The problem is what do you do with all the soot once you've collected it? You burn the soot or you toss the filter. Ford and Jaguar had to recall their diesels due to fire risk, and I think back in the 80s Mercedes did too.
> diesel is very small %
Depends of where you are. The share is very significant in Europe (it’s falling but still in the 30%-40% range).