You're a moron or a liar, or both.
Most European cities don't have any smog problems and those that have them aren't caused by diesel engines.
Wrong. Diesel engines produce high NOx emissions, which lead to smog.
Diesel engines may produce a little more smog than petrol engines, but they produces far less volatile organic compounds and fewer particulates, both of which are much more important to smog formation than NOx.
You're a liar. Gas engines don't produce significant particulates. Any idiot who's been around a diesel bus as it pulls away from a stop knows that diesel engines produce high particulates. Fuck you and your lying. Why are you lying?
Ah, yes, European companies like Ford, General Motors, Hyundai, Nissan, Suzuki and Mazda....
You don't know about VW's dieselgate scandal?? Again, fuck you and your lying.
Since most American truck makers are owned by European companies, there are probably quite a few in trucks near you, too.
Why are you lying so much? Cummins is not a European company, and Ford makes their Powerstroke diesels here in the US.