Nothing like the cars from the '70s or earlier. Every once in a while driving, I'll pass a restored car from the 60s or 70s going the other way, and can smell the exhaust for about a mile. And that's one car.
That reminds me of the Wartburg [1]. Our neighbor had one where I grew up, and us kids used to call it the "Atom bomb" due to the mushroom cloud of blue smoke it generated when it started up or pulled in.
Between those, the Trabants and the Serenas a morning in the former Eastblock would always look like fog. Heavy, worn out diesel engines of trucks and buses didn't help either.
The situation is now much better than when I lived there but even so Poland still has a huge smog problem.