It really is
the perfect solution to the problem of too many cars. Lots of people need or have a strong want for cars occasionally, and an inexpensive and convenient (it's certainly convenient for me, click click on the internet and then walk a block and a half to my car) way of obtaining that occasional car is perfect for urban dwellers who don't use it for the commute. And once you don't own a car, you're going to drive much less, as most of the cost of car ownership is perceived as fixed with relatively low marginal cost of driving an additional mile or hour. Car sharing takes away most of the fixed cost but increases the marginal cost.