On of the major sponsors of this year's Wired NextFest at Millenium Park in Chicago (Alongside Xerox and Citi), Toyota had plenty to show off. A large portion of the show's rear floor was devoted to a fleet of concept vehicles focused on, like much of the automobile industry these days, fuel economy and sustainability.

The latest Prius concept, the Plug-in Hybrid Electric Vehicle, is designed to stay in electric mode longer than its predecessors. The car can also be charged using a standard household three pronged outlet. According to Toyota, this latest rev of the company's popular green Prius line is due out in 2011.

Also on the four wheel side of the equation is the Toyota 1/X. This vehicle has the same interior space as the Prius, but weighs in two-third lighter, coming in under 1,000 pounds. That ultra-light weight lets the 1/X offer twice the fuel efficiency. The car is designed with rigid carbon fiber, which is reinforced by a plastic frame.

First introduced at the Tokyo Auto Show in 2003, the PM never made it beyond the prototype stages. It's lightweight, low-cost, and all electric. It also boasts a vehicle to vehicle communication system. The PM's successor is the i-swing, first introduced at the 2005 Tokyo Auto Show. With a two-wheeled upright mode and a three-wheeled cruising mode, this vehicle was the company's next shot at personal mobility. Like the PM, however, it never made it past the prototype stages.

As its name implies, the i-REAL has a much better shot than the two vehicles that proceeded it. Introduced at last year's Tokyo Auto Show, this vehicle boasts a walk and a cruise mode. It's the company's own personal Segway killer--just don't mention that to Toyota...