Why can't we use human energy from food to replace gasoline?

Question

Just think, if 100 people walked a mile, that would be enough energy to have gone 100 miles. Then why can't we invent machines that generate human energy to replace gasoline?

If say automobiles had pedals in each passenger seat so everyone could simultaneously exert energy and the car will then use less gasoline to get you where you need to go? Especially on busses this would put you at airplane speed.

Answer 1

It would require slavery to run your machines. That is why we don't have it.

Answer 2

There's a video of a guy in England who designed a four-seater to do exactly that. It goes pretty well, around 20 mph or so, but lacks such amenities as a top ('hood' in England.)

In general, humans don't  put out as much energy as one would like, about 1/8 horsepower for a  healthy young adult male, and that for only brief periods.

Answer 3

It won't help very much unless everyone is riding a bicycle, and we already have those.  Gasoline engines are amazingly powerful for their fuel consumption, size and weight.  

This is one of those schemes where you have to figure out the actual numbers involved in order to evaluate it properly.

Answer 4

sorry,

most people are just too d**n lazy to do that

Answer 5

build one for us then.

Answer 6

You are very right!  the Flintstones were so way ahead of their time!!!  Plus, you can always pedal a bike,