With car sharing, you can rent a vehicle for as little as a half-hour. Cars are self-service and parked close to where you live. Here’s the best part: when you carshare, the price includes gas, insurance, and maintenance and you only pay for the time you use. 

Car sharing is in operation in 17 major U.S. cities, and—thanks to a new, locally-owned company called CityWheels—Cleveland and Oberlin have had carsharing service since February 2006.  

In sufficiently dense neighborhoods, using a shared car is significantly easier than owning your own car. It can also save you serious cash, says CityWheels founder Ryan McKenzie, and it fits perfectly with an urban, high-tech (mobile phones, swipe cards and walkshed technologies) lifestyle.

Even better, car sharing offers major ecological benefits. Because as much as half the energy ever used by a car (and almost all of the material resources) are used not in the operation of the car but in its manufacture and disposal, sharing cars has an immediate and major ecological benefit attached. If three people share one car to do the same amount of driving they used to do in three separate cars, they have roughly one-third the backstory impact on those trips that they used to.

And it turns out that a lot of people can use the same few cars. Zipcar founder Robin Chase says that they have found that every efficiently-used shared car can replace as many as 20 private cars (that is, cars which users either sell or decide not to buy in the first place). That means that the backstory impacts of all those trips drops to as little as 5% of what it once was.

But the beneficial impacts of car-sharing don't stop there. Because car-sharers' driving time is limited and measured (most pay by the hour), they tend to use it more efficiently, making fewer trips and planning routes more effectively, all of which means that they tend to use less fuel to accomplish the same tasks.

Also, because the cars are being used more, they spend less time sitting in parking lots, and as car-sharing becomes more common, we can slash the number of parking spaces in our cities, greatly reducing the amount of space we need to cover with asphalt (if shared cars and carpools were given priority access to the remaining spaces, this would have the additional advantage of disincentivizing people driving alone. We may not go car-free anytime soon, but we could go car-sensible tomorrow.)

Though it may not be right for everyone, car sharing delivers most of the comfort and utility for less money and a fraction of the footprint of driving one's own car around.

Updates
Dec. 2006: Meet the Bloggers interviews CityWheels founder Ryan McKenzie  

Jan. 2007: Ohio Rideshare launches new site to advance carpooling (different than carsharing).