The strong demand on the OEM's to reduce fleet fuel consumption (CO₂ emission) enforces the technology development of fuel-efficient vehicle concepts. To achieve these goals R&D programs were launched to bring new powertrain concepts to market, e.g., hybrid powertrains as a combination of conventional and electrical systems, full electrical powertrains with range extenders as well as IC-engine-equipped powertrains with downsized combustion engines. The market success of these concepts will be decided by the realizable compromise of fuel consumption, driving dynamics and customer acceptance. The question, which optimum powertrain concept can be delivered to the customer, must take into account the cost/benefit ratio.With increasing interest in the development of Hybrid Electric Vehicle (HEV) and Full Electrical Vehicles (FEV), the demand for comprehensive system design and analysis to support the Powertrain Development Process (PDP) is rising. More advanced mathematical models of propulsion system components (both steady state and dynamic) are requested.This paper shows the approach setting up a development platform based on consistent simulation tools which are applied throughout the entire development process adjusting the simulation models to the requirements of the various development phases from concept phase to testing.Examples of such consistent methodologies together with the integration of simulation and testing tools are shown for the key tasks in the PDP as there are - Thermodynamics, combustion and emission development; - Mechanics development; - Virtual thermal management system development; - Hybridization and electrification (detailed presented); and - Calibration development.