There have been lots of failed common property bike experiments (e.g., here, here, and here), so what's a frustrated utopian to do? Try common property cars of course. From the April issue of Fast Company (p. 39; sub req):

The idea is to situate rows of cars at subway or bus stops or other high-volume spots. You would remove the first car from the stack and drive it to your destination. You could keep it as long as you wanted, then return it to another stack elsewhere in the city to recharge for the next commuter.

A photo of the stackable cars is here.

Note that this stackable car program is fundamentally different from existing car share programs (e.g., this one) because those programs register users. Registration of users creates a responsibility on the part of users to exercise care while driving and to return the cars. This linkage would be missing in the stackable car program.

HT: John G