[pchristensen]

It's a reflection of the physical limits of transportation. Even if you have a weightless car, you still have to move the weight of the passenger, who's a lot heavier than the electrons getting moved around in computers. Really, nothing in history has improved as fast as computer hardware, so it's reasonable to assume that most things won't.

That doesn't mean that huge advances are not possible - read Natural Capitalism by Paul Hawken to learn how 250mpg cars are possible with current tech.