The handy thing about "peak car" as a concept is that it can nominally be proven in many ways. You’ve got Peak Driver’s License. Peak Registered Vehicle. Peak Gas Consumption. Peak Miles Traveled. There are peaks per person, per household, per demographic. Then you've got your absolute peaks when you add up all of our vehicles and miles together, as if we were all cruising the highways at the same time.
Earlier this summer, Sivak released data showing that the number of registered light-duty vehicles in America (cars, pickup trucks, SUVs, vans) had peaked per person, per licensed driver and per household in the early to mid 2000s, before the onset of the recession. Because the U.S. population continues to grow, he predicted that the absolute number of vehicles had not yet peaked. But per person and household, we seem willing now to own fewer of the things.
She then goes on to show this chart from Michael Sivak:
Note that these peaks occur around 2004, demonstrating that this phenomenon isn't due to the recession. See more here. Also--and I'm not sure if my sample size is representative--the people I know in their 20-30s today don't seem to have the same interest in the conspicuous consumption aspect of car ownership that our parents' generation had.
Next we'll look at if transportation funding and home construction patterns (ie, size of garages) are following these trends.