No one mentioned rolling resistance when increasing weight- i can’t say offhand where that loss becomes significant or not but i believe it’s worth consideration. also, the energy doesn’t need to supplant the diesel engine but it could assist it. the real math is “can it carry its self, and more” and if so, “can it’s assistance save the fleet money over the life of its service”. i have my doubts but it doesn’t sound like anyone here or there wants to show any math…