According to this article:
German engineering consultancy Loremo is to display a fully working prototype of its super-economical coupe at the Frankfurt Motor Show. It revealed a mock-up called LS at Geneva last spring, demonstrating its plans to create a sporty-looking, ultra-lightweight four-seater capable of over 100mpg. The working prototype, called L1, is said to be able to travel 100km on two litres of fuel (equivalent to 117mpg), thanks to a tiny, super-efficient diesel engine and the car's low weight.
117 MPG?!? Check out the Wikipedia article for information about its range.
The X-prize, if you're not familiar, is an organization who awards huge sums of money to people who propose and prove amazing technological advances. The first was for a spacecraft, the new one is for automotive advances.
Imagine a world where super-efficient cars are desirable, affordable and everywhere... where gasoline no longer makes history, but is history... Revolution through competition.
Sound like good stuff. Blog here if you're interested in reading.