My alumnae magazine had an article on ZipCar (founded by an alum, of course). Car sharing is a proven concept in Europe, but is not widely used on this side of the pond. Zipcar lets you reserve a car for pickup at various parking lots in the Boston/Cambridge area. You pay a yearly membership fee, security deposit, an hourly rate and mileage rate. They give you a gas card to pay for gas, which is nice (and a good way for them to make sure the cars are kept fed). You also do not need your own insurance. They have a fleet of VW cars (new Beetles, Passats, Golfs, Jettas). Other cities have similar programs, both for profit and not (co-ops). San Francisco has City CarShare and Seattle has Flexcar.