Many of the world's cities lie under a permanent blanket of smog. People are concerned about global warming, and fuel prices just keep going up and up. It's no surprise therefore,that in recent years, car manufacturers have been put under pressure to invent a vehicle that is both cheaper to run and better for the environment. Finally, after much trial and error, it seems as though they might be making progress, and the future if the car industry is beginning to look a little "greener