It appears...for the first time in 40 years, the the total miles driven per year is taking a downward shift.
Of course, some would say that these reflect patterns in rising gas prices. But as you can see in the graph below: Gas prices have been rising for the past 40 years, as well!
Obviously, this requires much more in-depth research. But I suspect these are real structural pay-offs of urbanization. More people are living in areas that require driving or no automobiles at all.