Yeah, those models likely won't pass NTSHA crash tests, or cannot without $millions of upgrading. (The adding of weight is what is commonly done, and this sort of ruins the smallness of the car's key to being economical). Note that I am not saying this governmental involvement is necessary; Only that it exists.
If European standards for automobiles are anything like European standards for aircraft those European cars would probably be at the top of the list for crash worthiness. JAR standards for airworthiness are far more stringent that FAA standards......
You are correct concerning weight of todays vehicles. MY wifes new Honda Accord is 3,600 lbs!!!! WHATTTTT? Yeah, it is a V6 and the Accord is now a larger car than before. Weight is a primary killer to fuel mileage in town, during acceleration. Weight can often times be offset by aerodynamic stlying on the highway but no offsetting can be done in town.
3.600 lbs is the approximate weight of my old 1967 Dodge Charger with a cast iron 383 engine, a car I wish I had back. My wifes V6 is ALL aluminun.