Chris Casal, a Brooklyn, N.Y., elementary-school teacher, used to drive to work almost every day, mainly because it took 12 minutes compared with an hour by subway. But rising fuel and parking costs made the trip "kind of ridiculous," he says.

So last year he bought a Vespa GTS scooter that uses about $7 of fuel every two weeks instead of the $30 his Honda Civic consumed. He parks free in the schoolyard, and the two-wheeler impresses his students. The kids also like "the odd factor," he says. "I'm a six-foot-one-inch, 255-pound...