As resources become more scarce- as living spaces become more crowded- the car should become a means to an end, a tool, a utilitarian, functional conveyance. Maybe we could make them slower, lighter, more energy inefficient. An automobile designed for practicality, inexpensiveness, and maximum efficiency would look nothing like what we have today. Of course, we would lose the pride of ownership in our vehicles- but this is probably what must happen to continue to sustain our need to get from point A to point B.
Another feature of a revolution in personal transportation systems would be the dramatic shift in geopolitical power. The problems in the Middle East would suddenly become uninteresting to the developed world.
Short term transitional habits could include the imposition of a National 55 MPH speed limit- followed by engineering cars that would not be able to exceed this speed; Pricing automobiles at a rate such that it would be desirable and cost-effective to keep and maintain them for twenty years, or more; returning to an environment where the States emphasized the "privilege" aspect of licensing as opposed to the "right" of it. This could be accomplished by more stringent licensing requirements designed to reduce the number of drivers in private vehicles.
The bad news is that public transportation in much of America is simply never going to work, at least not in the next 50 to 100 years. Living and working patterns have developed in such a dispersed way so as to make mass-transit impractical for the economy to continue to function. As soon as we acknowledge this and put our efforts toward making private transportation more efficient, the sooner we can begin to solve some of our major transportation problems- In the meantime we keep letting the salesmen tell us the lies we want to hear.
Oh, wait a minute, this was a rant. Sorry.