If William Mitchell gets his way, the ubiquitous gas guzzler may not be long for this world—or could at least suffer a drastic reduction in numbers worldwide. The director of MIT's Smart Cities interdisciplinary research group says he has the luxury of tackling big stupid problems by "stepping back and asking the big stupid questions." Exhibit A: He and his team have developed a foldable, stackable, rentable electric car they hope will revolutionize urban transportation. Each joystick-controlled City Car would be part of a system with rental "docks" scattered all over town, specifically near transit hubs like subway and train stations. Just swipe a card and go.

1. ONBOARD BRAIN: These computers on wheels will "learn" as they go, monitoring traffic, weather, and so forth. Interior screens will reflect users' preset preferences, recognized via a swiped card. You'll be able to personalize the handling, display, and possibly even color. "For a shared-use system to work, you need sophisticated information technology," says Mitchell. A fully functioning City Car prototype—needing one-eighth the parking space of an SUV—could be finished by next year.

2. VISIONARY WHEELS: Since the folding car is joystick-controlled and recharges when it stops, there's no need for a steering column or bulky battery bank. Instead, the team created computerized, omnidirectional "wheel robots"—self-contained accelerating, braking, suspension, and four-wheel-independent-steering units with motors powered by lithium-ion batteries and a range of 50 to 75 miles per charge. Mitchell hopes to wrap them with airless, flat-proof Michelin Tweels, which would feature a honeycomb of polyurethane spokes. The motors may be capable of 190 miles per hour, but the plan is to cap the speed at 55.