SOMETHING BORROWED: Avis is leaping into the car-sharing service business by buying Zipcar for $491.2 million, aiming to capture a new type of customer and technology that will vastly expand its car rental options.

SOMETHING NEW: Car sharing has become a popular alternative to traditional rentals in metropolitan areas and on college campuses, allowing members to get a vehicle for an hour or two for short trips instead of renting a car for a day or using mass transit.