Generally, I think that vehicle should have an even number of wheels, three just seems unnatural, and unless you're a circus bear or a juggler, unicycles aren't particularly useful. But I have to admit that I was pretty taken with Charles Taylor's one-wheeler. The concept kind of makes sense for an off-road vehicle, and he had some success with his prototypes in the '50s and '60. Head over to Hemmings to check out some videos of his creations in action and get the full story behind these historical footnotes.