IN 2002, when the car-sharing company known as Zipcar brought its first 10 small Volkswagens to the city, an article in the Automobiles section of The New York Times offered the speculation that the venture's cars might one day "become as familiar to New Yorkers as the pushcart hot dog vendor."

More than five years on, that prediction is closer to being true. The company has 1,100 vehicles in the city, which can be picked up at more than 100 different sites.

But as the company grows, it has bumped into a problem facing so many New Yorkers: scarce and expensive parking. Zipcar says it raised rental rates last month in part because of this cost, and as the company expands further outside Manhattan, it finds itself struggling to stay a step ahead of the developers who are buying up the city's empty lots.