Just... wow. Talk about misinformed.
Your analysis of diesel cars would have been accurate 10 years ago, but it doesn't hold up nowadays. Modern diesel engines are just as clean as an equivalent petrol engines (modern diesels have had very effective particulate filters on them for quite a few years now), far torquier, return 30%-40% better fuel economy than an equivalent petrol engine and often have much longer service intervals. They're just as quiet these days too. They just haven't taken off in the US because of the lack of availability, until recently, of low sulphur diesel, and the different criteria used for emissions here, not to mention a perception of diesel as the preserve of trucks and tractors (a perception you obviously share).
As for European cars being unusable in the States... absolute rubbish. Firstly, your point about safety... the Euro/NCAP safety tests are more stringent than the NHTSA tests in terms of vehicular impacts, plus they also test for pedestrian impacts, which the NHTSA tests kinda skirt over. I'd go as far as to say that most Europe-produced cars are actually safer than their US equivalents. Plus, you'll find safety equipment such as ABS, EBD, traction control, curtain airbags, etc installed as standard equipment in almost all European cars, where they're often only sold as options on US cars. And, as for the size thing, not everyone drives sub-compacts! There are quite a few around, but I'd say the typical size car you'll see in Europe will be something along the lines of a Mazda3 or Cobalt, with larger families driving smaller MPV-style vehicles - the nearest equivalent sold in the US would be the Mazda5. These all have plenty of room for 5 people (and, in some cases, 7 people) and all their stuff. You don't see big SUVs or trucks there, mostly because they're a) too thirsty, and b) they just don't fit on the roads.
And I have no idea where you got the idea that European cities have a smog problem... I used to live in London and haven't seen smog since I was a little kid, nor have I ever seen smog in any other European capital I've ever been to, including hotter cities like Madrid.
The vast majority of problematic diesel emissions come from older diesel trucks and buses that were never fitted with catalytic converters or particulate filters - not from diesel cars. If you got rid of those old vehicles (or even upgraded them), you'd eliminate 99% of the problem right there.