Younger people today -- in fact, people of all ages -- no longer see the car as a necessary expense or a source of personal freedom. In fact, it is increasingly just the opposite: not owning a car and not owning a house are seen by more and more as a path to greater flexibility, choice, and personal autonomy.
Underlying all of this is not so much a shift in "car culture" values but a shift in economic realities. Owning a car and a house are very costly, for individuals and the economy as a whole. What distinguished "savers" from "spenders," according to a Canadian study (.pdf), is outlays for housing and especially for cars. The amount of money the average American family spends on housing and cars went from 22 percent in 1950 to 44 percent by the 1980s to more than half today. It's not so much that America is a society of wanton over-consumers -- though some surely fit that bill -- it's that they've been trapped by the housing-car-energy complex that once stood at the very heart of the U.S. "Fordist" economy. And as any number of studies have shown (.pdf), America's over-investment in housing has badly distorted its economy.
But what this also shows is that change with the right incentives is possible. Imagine the impact of a dollar tax on a gallon of gas, balanced by a FICA cut.