It's interesting to note a new trend uncovered by the public advocacy research group U.S. Pirg—young people have officially begun to lose interest in driving. After six consecutive decades of unimpeded growth in driving rates, they began to stagnate in the mid '00s.
Some interesting statistics on mobility, but I'm not sure that you can prove the Internet caused the decrease since there's also a huge cost to owning a car that the economic downturn probably discouraged.