Isn't there a chicken-and-egg problem especially in US cities? The typical low-density suburban sprawl in american urban areas was "fueled" by the car/oil and housing industry in a much larger scale then in other similar developed countries. This lifestyle was nothing less then the american dream - no? In the same time the economy and the urban centers are expanding and everything is built around the autombile lifestyle. So yes, today it wouldn't be possible to simply scratch the car out of the equation, simply because it's heart and center of the urban america. But without the onesided accent on individual motor car traffic, america would probably have a different landscape that made public transport much more cheaper and convenient.