Car sharing has grown in popularity in recent years thanks to the internet and smartphones. But now the city government of Helsinki, Finland, wants to take that idea to its logical endpoint: replacing most privately owned cars by 2025 with a comprehensive route-planner app that would also offer access to all of the city's shared-transportation options, plus weather forecasts. As The Helsinki Times reported earlier this month, the idea is to offer every commuter a series of transportation options tailored directly to them and their circumstances: so if it's due to start raining, the app would recommend exactly when to swap a bike-share for a cab, for example.

The idea, "mobility as a service," was first proposed by transportation engineer Sonja Heikkilä in her master's thesis (commissioned by the city government). It will start modestly at first, with the city government set to perform tests in early 2015 in the Helsinki neighborhood of Vallila. The government plans to expand it from there to other neighborhoods. Heikkilä's idea calls for flexible payment models, offering various packages such as paying by the kilometer, or monthly passes. It's an ambitious proposal, and as previous experiments in making public transit smarter have shown, it may be more complicated in practice than in theory. But with car ownership already clearly declining in some key urban areas, it may be an idea whose time has come.