The concept of selling mobility on demand rather than cars themselves may be finally gaining some traction. Remember the stackable urban rental cars proposed by GM-funded researchers at MIT last fall?

Well, Paris is working hard to make that vision a reality. The French capital is gearing up to offer the auto equivalent of Vélib, a distributed bicycle-rental scheme that provides more than 20,000 bikes at more than 1,400 sites across the city and the suburbs. Paris mayor Bertrand Delanoë announced in June that the city will place 4,000 small electric cars at 700 Autolib pickup points around Paris and the suburbs starting in 2010. And according to business daily Les Echos (story en français), train giant SNCF is vying to operate the Autolib points out of its train stations, which are distributed across and around Paris.

And now, the city may finally have a solution to a potential game-killing problem: the uneven distribution of vehicles as cars pile up at popular destinations. Parisians are well aware of this problem. By midmorning, for example, as Vélib stations at the periphery of the city empty out and those downtown jam up, it’s not unusual to see trucks redistributing the bikes to counter the tide. That’s easy enough with bicycles but harder to envision with even small electric vehicles.

The city’s solution? According to a leaked document reported by auto-news website Caradisiac (again, story en français), the plan is to simply have users declare their destination upon checking out a car. In response, the system will determine the closest Autolib point with a free spot for drop-off and reserve that space. No news on solving another potential problem for Paris’s Autolib scheme: the name. Lyon, which beat Paris to the bike-share program with its own vélo’v, already sports a conventional car-share program called Autolib.

Could a similar scheme work in the U.S.? Issues of Forbes magazine that will appear on newsstands next week tout the MIT City Car concept as the embodiment of a new car-sharing direction for troubled automakers. City Car codesigner Bill Mitchell of the MIT Media Lab’s Smart Cities group adds to the drumbeat in a recent editorial for architecture website BD. “People don’t want cars, they want personal mobility,” writes Mitchell. He argues that, rather than bailing out car firms, governments should be radically rethinking urban transport around ultralightweight battery electric vehicles (EVs). To provide mobility most efficiently, says Mitchell, we should

… organise urban electric cars in mobility-on-demand systems like the Vélib bicycle system in Paris. Racks of public-use cars would be provided at closely spaced sites across the service area. If you want to go somewhere, you walk to a nearby rack, swipe a card, pick up a car, drive it to a rack near your destination, and drop it off.