Volvo has tested a concept that doesn’t use gasoline or even have an engine, but it does need to be on an inclined plane though. The Volvo concept uses Sir Isaac Newton’s fave force to power it, propelling it up to speeds of 54mph. Though fastest in the Extreme Gravity Competition held in California, which saw other automotive heavyweights such as Audi and Bentley competing, you won’t see this concept on the road ever.
Fuel prices, pah! Get a gravity powered car (T3)