Here's a documentary, Greasy Rider, about two guys going across the country in an old mercedes veggiemobile.
[youtube=http://www.youtube.com/watch?v=0rxIugs5FZ0]
Our former intern Michelle, just back from Iceland, told us about it.  Next week she's picking up her first veggie oil-powered mobile - a '96 Ford  F250 extended cab truck - blue with pretty white side trimmings.