A tool for holistic energy simulation and optimization of urban rail vehicles is presented. The modular vehicle model consists of easy to parameterize subsystems. All essential energy consuming subsystems (traction system and auxiliaries) can be considered via models of adequate detail level. Interaction between subsystems is simulated and driven by the operational conditions and internal controllers. Apart from energy signals the tool provides many other time signals, which contain valuable information for the vehicle manufacturer. Different workflow variants of the tool enable a case specific simulation or optimization. Furthermore a superordinated multi-objective mixed-integer optimization (MOMIO) can be applied to optimize the rail vehicle with respect to design parameters and operational conditions. Additionally a Brute-Force-Method (BFM) simulating all possible combinations enables to analyze the sensitivity of objectives (e.g. total energy) with respect to the selected design variables.