This is YAOTT (yet another off topic thread.)
I looked at the picture. The thing is efficient because it doesn't let you use it inefficiently. With a car you can step on the gas pedal and burn a lot of gasoline, then break, step on the gas pedal etc.
This thing, when you speed up, will increase speed at a steady rate exactly fast enough (and slowly enough) so that you don't fall down. It basically keeps you in the upright position by either slowing down or speeding up.
I can see several problems with this. First, this thing is accident-prone. Try this: stand up, then start walking forward. You'll notice that the first thing you do when starting to walk forward is start falling forward, then you'll move one of your legs forward. What happens when you stop? You have to start falling backwards, so that the energy it takes to lift you up will cancel out the kinetic energy of your body moving forward. You achieve this by moving your leg forward farther then usually, then arching your back a bit.
This scooter obviously doesn't have any legs, so the only way for it to stop is to speed up so that you start falling back, waiting for you to start falling, then slowing down so that by the time you are in a vertical position you are no longer moving. So think about this, some kid jumps out in front of you, you hit the stop button (or however that works,) and this thing actually speeds up. The faster you go, the more this would be a problem (and the slower you go, the more useless this thing is.)
Obviously this is not a problem with two-wheel scooters, as the front wheel is already quite a bit in front of you.
For the same reason a two-wheel scooter is much safer when you hit something. You hit something while riding The Segway, and you get to meet what you hit face to face, plus you get emotionally attached to the handle bars. This will be true even if you hit something low, like a curb, unlike a two-wheel scooter this thing will fall right over.
And I'm not sure where I would use this. This thing won't make me move back to the city, so do I put this in my trunk and basically use it to move from my car to my office? Where do I park it, in my office closet?
voodoo