The least-explored, least commercially successful, most fantastical motorized vehicle of all time must be the monowheel. Shown are turn-of-the-century inverted unicycles juxtaposed with modern in-wheel V-8 screamers. Some of these vehicles seem cartoonish and inefficient, others terrifying. The fatal flaw of the genre is the phenomenon of “gerbiling,” wherein the rider gets looped around inside the wheel during breaking or acceleration like a hapless rodent. There’s a great MPEG of a diwheel in action too. Thanks boing-boing.