Toyota’s 1/X Concept is pronounced one-Xth, not one over X. The X also does not mean 10, instead 1/X means the vehicle is only “1/Xth” the weight of other vehicle in its class, whatever class it may be. It represents a new idea of what it means to be environmentally considerate.
This particular 1/X Concept car shown at the 2007 Tokyo Motor Show takes the current Toyota Prius as a basis of comparison. It maintains the same interior space with that of a Toyota Prius, but only weighs 420kg, which is one third the weight of the Toyota Prius. The result is a target of double the fuel efficiency of the Toyota Prius.
This reduced weight is thanks to a light but highly rigid carbon fiber reinforced plastic body frame. This also allows narrower pillars for better visibility from inside the cockpit.
The 500cc hybrid powertrain is a combination of a FFV (Flexible Fuel Vehicle, capable of running on a mix of gasoline and ethanol) combustion engine and an electric motor hooked up to batteries with plug-in charging capability. This hybrid system is located at the rear of the car under the rear seat bench, effectively giving the car a midship rear wheel drive configuration.