It seems almost too simple: one card that gives access to the trains, buses, and a local car-sharing program. The Smart Card is Chicago-based nonprofit I-Go Car Sharing's idea to extend public transportation to include public cars. According to a recent study, most cars in Chicago -- Fast Company's 2008 City of the Year  -- sit parked 95% of the time. "We have to make better use of our assets," says I-Go CEO Sharon Feigon. "We want to integrate the public-transit systems and car sharing any way we can, and sharing one card is a good way to demonstrate that these different ideas are linked." The pilot program started in January with 5,000 Smart Cards and more than 200 cars. Coming soon: shareable plug-in hybrids that can power up at kiosks with real-time info on buses and trains.