Here's a bit of interesting news on car sharing companies, which, according to The New York Times, are catching on a bit in Europe. The most salient bit:
Studies suggest that one shared car replaces 4 to 10 private cars, as people sell their old vehicles...The result is a 30 to 45 percent reduction in vehicle miles traveled for each new customer.
Now, 30 to 45 percent is a pretty sizeable decline in driving. But this shouldn't come as too much of a surprise; as any economist would predict, converting a fixed cost (e.g., the cost of buying the car) to a variable cost (e.g., the cost of renting a shared car, which for Seattle Flexcars costs up to $9 per hour) makes people far more selective about how much they drive. And that probably saves car-sharers money overall: Yes, they pay more for each trip, but they make fewer trips, and also avoid much of the expense of purchasing and maintaining a car for personal use.