Henry Ford built a car built from hemp fiber and fueled with hemp oil/alcohol fuel. It was completed and writen up in Popular Mechanics in 1941 and is an easy search on google.

A great idea killed with the law against INDUSTRIAL use of hemp.
ArtRollins Reviewed by ArtRollins on . Eureka! How about a weed-powered car? Actually, nah.. that would be pointless. After the fast time you filled it up it'd just want to be filled up with Pringles and Coke. It'd probably keep getting lost too. Scrap that idea. How about a weed-powered robot? Rating: 5