Due to the growing complexity of powertrain systems,an efficient development process increasingly hinges on early eval-uation testing of concepts under realistic conditions in the context of the whole vehicle.The question of energy efficiency,emissions and driving performance is crucial and indispensably requires a holistic evaluation under real driving conditions.This paper presents an ap-proach to ensure efficient powertrain development by means of virtual powertrain electrification on the engine test bench.In comparison to road tests with prototype vehicles,the virtual test driving approach allows for highly flexible and reproducible tests with significant reduc-tion of time and costs.