"As we've discussed, gasoline prices are just part of the story. The lack of growth in miles driven over the last 5+ years is probably also due to the lingering effects of the great recession (high unemployment rate and lack of wage growth), the aging of the overall population (over 55 drivers drive fewer miles) and changing driving habits of young drivers."

http://www.fhwa.dot.gov/policyinformation/nhts.cfm

Why Young People Are Driving Less and What It Means for Transportation Policy http://www.uspirg.org/reports/usp/transportation-and-new-gen...