While energy experts worry that world production of oil has already peaked -- "peak oil" -- a different phenomenon may eventually require less oil in the U.S.: younger Americans are driving less, according to reporting by John Schwartz in the New York Times (May 14).  The main source is a report by the U.S. advocacy group U.S. Pirg; author Phineas Baxandall said the changes don't appear to  be related to economic recession and seems to be part of changing demographics: "Millennials aren't driving driving cars," he said. Research by Michael Sivak at the University of Michigan found that young people are getting driver's licenses in smaller numbers than in previous generations; simultaneously, baby boomers are aging out of the workforce and therefore driving less. The Michigan study found that less driving is correlated with increased Internet use, suggesting that younger Americans are spending more time in front of the computer, and less behind the wheel. The Times article focused on experiences in Charlotte, N.C., home of a new light-rail system.  One young worker decided to switch to public transit after visiting New York, but reports that riding the bus is less socially acceptable in Charlotte: riders look askance at those wearing office attire, sometimes wondering if the officeworker's driver's license has been suspended, perhaps for D.U.I.  In Charlotte, the light rail line was supposed to reach a goal of 12,000 riders in 7 to 10 years, but hit the target in the first six weeks. President Obama has nominated the city's mayor, Anthony R. Foxx, to be the next Secretary of Transportation.  But other transportation pundits said the change in habits might only be temporary, caused by high unemployment; once the younger generation acquires enough money, they may well move to the suburbs and need to drive.  And cars that drive themselves, a distinct possibility in the future, might attract more drivers, including elderly who might otherwise give up driving.