... Also because electric regenerative braking requires a battery and electric motor (for propulsion, the starter is useless for this). Once you fit regenerativ

... Also because electric regenerative braking requires a battery and electric motor (for propulsion, the starter is useless for this). Once you fit regenerative braking into an ICE vehicle it becomes a hybrid vehicle, leaving no ICE vehicles with regenerative braking. :) (I don't think you would call a vehicle with mechanical KERS system a "hybrid", although it technically is as there are multiple propulsion systems in the vehicle.)