Toyota 1X Concept
The Toyota 1/X (pronounced one-Xth) is a concept car built by Toyota and first shown at the 2007 Tokyo Auto Show. It is a petrol-electric hybrid vehicle utilizing plug-in technology. The car weighs only 926 pounds (420 kg) but has as much interior room as the Toyota Prius. The car's frame is mainly carbon-fiber reinforced plastic, which allows it to be light weight yet strong. The engine is 500 cc and sits under the rear two of four seats, driving the rear wheels.
Toyota envisions the car to be made of seaweed in the future.
Source: Wikipedia, 2011