Thanks

http://lightspeedtransporters.com/

Likewise, there's the informal carpooling/sharing that happens at many locations in the Bay Area where people, often strangers will fill a car up with folks all going in the same general area (downtown SF, etc) and that helps too.

Zipcar et all are nice, but they're not the only way to share the use/expense of a car when you can't take a bus or a train.

1 person per car on 'free' roads just doesn't scale to 6 billion+ people for most of their journeys. Not if you also expect the fuel source to be cheap, and have a viable planet.

CarSharing is one business model among many that has to step into the breach, and maybe make some good money at it too!

So I would say that in our case, having City Carshare as a lightly-used back up does reduce our contribution to city congestion. (It also saves us $7000 annually and means we have room in our garage for our seven bicycles.)

I'm wondering what types of trips people find it useful for. If I need a car to go out of town, I rent. If I need one to go somewhere in the city, which is rare, I call a car service or hail one on the street. No parking hassles or drinking and driving issues.

I first signed up for the service after I had to take the LIRR and then a cab to a Sunday night wake for which I could only stay for 50 minutes due to the train schedule. But I haven't had another situation like that since.

In most parts of the country, there should be little doubt that it would reduce total auto travel. There are, however, reasons to suspect it could actually result in particularly dense places like NYC where current car ownership rates are low.

By making cars more accessible to a population of drivers with limited access, you could expect an increase in driving trips.

There are complications, of course. By improving parking availability and managing it better, there should be less cruising for open on-street parking spaces, which would have some reducing effect on traffic. And some people who have cars may give them up, making them likely to make fewer trips by car.

How these various factors would balance out is far from clear. The benefits from the reduced storage requirements alone make it look like a good idea, even in these situations. But it is worth considering that the results may not necessarily be a net reduction in VMT.

Disclosure: I'm a City CarShare employee.

They're both great. I use zipcar, but I'd be perfectly happy to use one of the traditional companies if it were around the corner and had insurance and gas built in, and I didn't have to wait in line to make small talk to an employee.

I usually get a zipcar by the day to get out of town. It's not so much cheaper (maybe slightly) than Hertz or Enterprise, but it's a whole lot easier.

Disclosure: I'm a happy Ithaca Carshare member.

It is a for-profit business based on sharing a single car between many potential drivers.

Peer-to-peer car sharing is something that is still developing, where the car is actually shared, thats different.