Jesse Ausubel sends along a link to his recent article: Cars and Civilization (pdf).

Rising incomes mean rising speed at all social levels. The rich, of course, accelerate more than
the poor. While poor means slow, even the slow today speed when compared with Queen Victoria.
In industrial countries, a poor man has a car and mobility superior to an ancient nobleman and at least equal to the Great Gatsby. When new travel modes are introduced, such as supersonic Concorde planes or maglevs, they will first be the province of the rich.

Worth reading if you like S-curves, travel time budgets, and other Macro-transportation topics. (Which of course, I do.)