Nowadays powertrains face an increased customer expectation regarding noise and vibration. The virtual product development (VPD) has reached a comparative high standard for the NVH simulation of powertrains. Modern simulation tools allow a target-oriented NVH simulation with regard even to audiable vehicle interior noise. Due to a consequent utilization of VPD the saving of one physical prototype is possible. This trend requires a front-loading of developing resources in early phases of the power train development process. Therefore FEV is using virtual development methods for NVH optimization of powertrains for more than ten years. Multi-Body simulation systems will be used in order to simulate the dynamic performance. Fully parameterized simulation models allow the utilization in all phases of the development. Depending on the current design status of the development the detailling of the simulation models can be adapted. Based on comparative simple rigid body models in the beginning decisions regarding eingine global data like bore, stroke cylinder distance and positioning of balancer shafts can be made. Later on, when more design parameters are fixed, the depth of simulation models is increased until a fully flexible model allows the prediction of the NVH behaviour of the complete powertrain. Such a simulation is performed using a hybrid simulation approach based on Finite-Element and Multi-Body simulation. In a second step the FEA model of the powertrain is loaded with exitation forces calculated with MBS in order to calculate surface velocity. Based on these results further simulation allows the simulation of the airborne noise radiation of the entire powertrain. Taking into account that vehicle interior noise has become more and more important especially in terms of sound quality, the simulated airborne and structure borne noise can be combined with Vehicle Interior Noise Simulation (VINS) developed by FEV, which leads to a synthetic interior noise at the end. This procedure has been proven in numerous projects and reported in several publications. While in the begin simple and fast estimations dominate the process, at the end an audible virtual interior noise is available for the NVH assessment of the powertrain.