OT: I was thinking: Imagine how easy self driving trains are to make. Then I naively pondered if air filled tires are all that efficient. I cant imagine bending

OT: I was thinking: Imagine how easy self driving trains are to make. Then I naively pondered if air filled tires are all that efficient. I cant imagine bending the rubber gives back a lot of energy? I just looked it up: "An average truck gets around 150 ton-miles per gallon of diesel. Trains get around 600 ton-miles per gallon."