The idea was conceived as a solution to the population growth that is fueling (pun intended) traffic congestion. The “City Car” as it’s currently being called, will be based on the shared car model that the ZipCar is currently proving viable. Stacks of cars would be placed outside office buildings, schools, and any other high-congestion areas.
ZipCars need to be returned to where they were picked up, which can be a hassle. It appears that all City Cars will be the same model and won’t need to be returned to the same place. Tropist is headquartered down the street from MIT and we can understand their interest in this project–often the only place to park would be on top of another car.