"It is quite obvious that most US-ers will not abandon the use of their cars even if they have more efficient and less costly means of transportation available."
That's a big IF Woj. The problem with the US is that there is no more efficient, less costly means of transportation available in most cities. I used to live in LA. While I was a student and my transportation needs were getting to UCLA and back, the bus was great. It helped that I lived two blocks from the bus stop and that the bus ran me to campus: bus time 40 minutes; car time 25 minutes. It's also true that when I'm in Europe I rely entirely upon public transport and get around very easily and pleasantly. But the cities in Europe are small compared to U.S. cities and very well provided with public transport.
But, as a single mom in the bay area (public transport very, very bad),I cannot get by without a car. Remember that people with kids not only have to take care of their own transport needs (work, shopping), but also that of their children: school, extra-curricular activities, visiting friends, etc. And many cities are built for cars: they're wide-spread and have very inadequate public transportation.
I lived for a couple of years in Plattsburgh, New York. Small town, no public transit, but everything was within walking distance. I had no car and did not miss it; I walked everywhere. This had the most salutary effect on my figure and health, but such towns are few and far between.
Joanna