What is the most efficient man-made transportation mode?

efficient = minimum inputs, maximum output, minimum waste

land based - bicycle, especially a recumbant,with streamlined fairing, even more efficient than walking shoes; possibly a fully ocupied electric train for long distance & heavy load.

Lifts (elavators) are possibly even better.

on water - sailing boat or kayak depending on water conditions and length of journey & load.

By air - ballon

If we see in our current era of life then I must say the car is the best way of transportation as a private transportation and Train is best at Public Transportation.

Good Question...

I would go for a Ship... My reasons are...

Its the only transport mode to which the natural causes aid.. (The stream and wind).. and also is much cheaper affair than air travel.. agree?

Probably the car - we all seem to have them.

Although my ex-wife prefers to fly around town on her broomstick.

bullet train

bicycle

surf board.