@mewmew you included the energy required to produce the energy the walkers used... Should you do the same for the gasoline? Extraction, refinement, transportation... Amortized production of the vehicle. Pollution.
I would think the energy used in building roads would amortize down to nothing, but the valuable real estate taken up by road in some places certainly has a cost. If only considering energy efficiency, consider that folks might not have to walk a mile if things were closer together.
@mewmew wow! Yeah. That scientific american article points that out. Thanks, very interesting.
@mewmew that's just how inefficient our massive food production system is. We gotta get things on electric and get the grid more sustainable.