Even modern cars pollute a lot (especially in winter) because you need a certain temperature for the cats to start working. On short city trips it happens frequently that you never reach proper operating temperatures.
Regardless, there’s nothing cleaner than no combustion, and I can’t wait until EV‘s have replaced them all
Also at some point they will start their engines again. Guess who will inhale that?
Sources: https://usa.streetsblog.org/2019/10/08/report-drivers-arent-... which references the BBC
Most start stop systems will disable themselves when the heater of the car is turned ON and the car engine not hot enough yet.
As a cyclist (or motorbike owner), it is pretty usual in city to have >50% cars with engines ON at traffic light in cities when temperature are low.
You've got the added bonus that you don't need to strip-mine huge chunks of Africa for precious metals, too.