GM unveils super-efficient car

Troubled auto giant General Motors said yesterday its new electric car, the Chevrolet Volt, will be marketed in 2011 as the world&rsquo;s most fuel-efficient car.<br /><br />The Volt is expected to achieve city fuel economy of at least 230 miles per gallon, and can travel 40 miles on electric power alone. The record-breaking level of fuel efficiency beats every other mass market vehicle currently on the road, including the Toyota Prius. GM says the technology for the car is expensive.