Zipcar has been parking their Minis and Priuses closer and closer to my office, and now parks cars in two locations, each only two or three blocks away. One location has a Honda Insight and a Volvo S40, the other has an Insight and a Toyota Tacoma pickup truck. I wish Zipcar had been this close two years ago when I sold my my 13 year old car to a kid at the shop rather than spend $750 on needed repairs.

Public transportation required too many connections, so for over a year, I was spending about $46 to rent a subcompact car for a full day from Enterprise just to attend meetings in nearby Catonsville. Renting Aveos, Versas and Calibers was cheaper in the long run than buying a new car and paying for city parking, but Zipcar would have cost me only $8/hour - plus the $60 annual membership and $25 application fee. Sigh.

Car sharing didn't start with Zipcar. Auto-Marxists in Montreal, Quebec City, Gatineau and Sherbrooke have offered Communauto since 1994. Montreal is now trying to integrate the car sharing scheme with Bixi, their bike sharing service.

Zipcar started in Cambridge MA in 2000, acquired Seattle-based Flexcar in 2007, and seems to be expanding. But it isn't yet profitable. And although their IPO went well, financial types warn that Zipcar's real rivals will be Enterprise, Hertz and Avis - companies with thousands of locations. Of course, when the personal computer boom started, Radio Shack had thousands of locations, too.

I used to ask about car-sharing at Enterprise, and was met with a blank stare, but they now have a car sharing site called Wecar. Hertz has a car sharing site called Connect. Both of these programs seem to be targeted at college campuses. I met a lot of ambitious young people at Enterprise desks, trying to keep the customers happy on the old rent-a-car model, but there's a lot of standing around while they try to upgrade you, while they try to sell you short term insurance, while they move cars around and they usually aren't open on Sundays. I think it will be as tough for them to switch seamlessly to the sharing business model as it was for GM to embrace the smaller vehicle market.

But with fuel costing more, and fuel-efficient cars costing more, and jobs harder to find and keep, it makes sense that city residents are going to want more options for short term transportation than cabs and rental cars.