Among conventional 4-cycle ICE designs there are some recent generator and marine applications near 50%. F1 designed an amazing hybrid system that achieves 50%

Among conventional 4-cycle ICE designs there are some recent generator and marine applications near 50%. F1 designed an amazing hybrid system that achieves 50%. Those are the best figures I've seen. The F1 hybrid design is pretty amazing. The motor–generator is driven by and drives the turbocharger. This allows the turbo to be optimized: When the turbo wants to spin too fast electricity is generated and when the turbo would otherwise not deliver enough pressure (lag) the motor–generator augments the turbo speed. Excess stored power goes to the drive train. This effectively solves turbo charging, recovering waste heat through all operation phases, eliminating lag and delivering high efficiency. F1 chose not to field it, and I don't know why. I don't know if it will ever be seen in normal applications.