These concept vehicles won't enter production, but they provide some food for thought concerning the needs of future commuters winding through narrow streets or alleyways. And given global trends, it's safe to say that the cities of the world will only become more crowded in the near future. If you're not down with a regular bike or a full-blown car, perhaps an affordable single-seat vehicle might not be a bad alternative, unless GM's two-wheeled P.U.M.A. somehow takes off in a way that the Segway didn't.