At inhabitat, they look at a new car that runs purely on coffee grounds. The 1986 Volkswagen was re-designed to run off of coffee grounds. Designed on the show Bang Goes the Theory, Nick Watson, the producer of the show, says this of the car, 'Coffee, like wood or coal, has some carbon content so you can use it as a fuel. The coffee needs to be very dry and in pellets to allow the air to move through the pile of coffee as it burns. The brand doesn't matter.'
While using waste to fuel the car, it can get pretty expensive, as it takes a kilo of ground coffee for the car to run three miles. So while it is innovative, the search for an efficient alternative fuel source will continue.