Segways glide through theme parks, around warehouses and along Silicon Valley pavements, but are seldom seen elsewhere.

I don't know if people will be using Segways to get around cities in 20 years' time, but I do know they won't be using cars.

Inventor Dean Kamen displayed his Human Transporter, a two-wheeled, motorized scooter that costs less than US10 cents a day to run.