Oct 17, 2019 · Half the energy generated by an internal combustion engine is wasted as heat, whereas electric drivetrains used by FCEVs only lose 10%. Nikola Motors, a U.S. maker of hydrogen trucks, claims its vehicles can get 12 to 15 mpg, well above the average 6.4 mpg for a diesel truck. But hydrogen production needs to scale up rapidly and reduce costs.