Concerning "cars per 1000 people," list here: http://en.wikipedia.org/wiki/List_of...les_per_capita
A related issue is the urban sprawl concept of the United States. The desire to have a bigger house and own more land -- and doing so by moving farther and farther outside the city limits. As a result, we rely on cars more -- and put more miles on them.
Yes, a greater percentage of Europeans are more than happy living within the city... oftentimes, in very small flats and minus any land of their own. In the U.S., this tends to be for either the very rich or the very poor. So yes, the middle class does "need" their cars as a result (well, and other other classes as well).
Again, it would take a change in mindset. We are a much more materialistic society than the rest of the world. Wanting our cars, big houses, big yards, boats, etc.
I would love to see a massive, extensive, efficient, reliable mass transit system in our country -- but it's not going to come easy -- and not going to happen without some sacrifice, I'm guessing.