NEW YORK (AP) — The ability to access a car quickly and give it back after a few hours is exploding in popularity among both college students and city dwellers.

Zipcar created the car-sharing concept in 2000. By the end of the decade car-sharing had caught the attention of the two largest U.S. car rental companies as Enterprise and Hertz started competing services. And this week, Avis, the nation’s No. 3 car rental company, jumped into by offering nearly $500 million to buy Zipcar.