I saw the "World's Fastest Wood Burning Car" at the Mother Earth Fair last September.
It was pretty cool.
Mercury Beaver XR7 – Worlds Fastest Wood Powered Car | Beaver Energy
Also, technically it's a dual-fuel vehicle. It was set up to be able to run on gasoline OR wood. (The wood-gas goes in to the AIR INTAKE!)
When I saw it fired up, it was started on gasoline, but run on wood-gas.