As someone who grew up with leaded gas and carburated cars, I don't really miss them. I pull up in traffic these days behind an old restored muscle car (which

As someone who grew up with leaded gas and carburated cars, I don't really miss them. I pull up in traffic these days behind an old restored muscle car (which are awesome, don't get me wrong), and the smell of unburned gas makes my eyes water. It's hard to believe that all cars were like that. I think the article is mostly referring to diesel emissions though, since they refer to the PM-25 particle size, commonly produced as soot from diesels. The new diesel exhaust fluid (DEF), particulate filters, and computer controls have come a long way in reducing the soot produced. But they're complex systems that tend to have a lot of problems. And as we saw with Volkswagen, they can be gamed.