"ZipCar, an innovative Cambridge-born car-sharing business, operates in Boston, New York and Washington, D.C. But nowhere has it become more a part of the transportation fabric than Cambridge, where about 3,500 residents use the service.
...About 3.5 percent of Cambridge's 100,000 residents are active members of ZipCar. That's good penetration, given that ZipCar's goal is to have 10 percent of residents use its service."
Thanks to Laura Kranz