Zipcar is a membership-based car-sharing company founded in 2000 at Cambridge, MA. It has become the world's largest car-sharing service, sharing 6,000 vehicles among 275,000 drivers in 49 U.S. cities, Vancouver, Toronto, and London, representing almost half of all car-sharers worldwide.

Members, whom the company calls "zipsters", are able to view vehicle availability and reserve a self-service car via the internet, iPhone app, or telephone by hour/day. Zipcar vehicles report their positions to a control center using in-car technology.

Members are given a "Zipcard," an access card containing a wireless chip that will open the vehicle they have reserved only at the time they have reserved it. The reservation includes driver's insurance, a gas card for the car, reimbursements for fuel obtained at gas stations that do not accept the included gas card, and up to $15 in reimbursements for typical car maintenance items like car washes and window wiper fluid refills. A member can reserve and use a Zipcar in any Zipcar city.