The V-Cycle is a well accepted and commonly implemented process model for systems engineering. The concept phase is represented by the upper-left portion of the V, in which very high level system simulations are the predominant modeling activity. Traveling down the V toward the vertex, sub-system level and component level simulations are employed as one enters the development phase. Finally, the test and validation phase is completed, and is represented by the right side of the V.Simulation tools have historically been used throughout some phases of the V-cycle, and with the ever increasing computing power, and the increasingly accurate and predictive simulation tools available to the engineer, today it is common that simulation is used in every phase of the cycle, from concept straight through the test and validation phases. However, until recently, the modeling and simulation activities performed throughout the development cycle involved the use of many unique and disparate tools, each with a specific specialty. This paper presents the use of a single simulation tool throughout all stages of the development cycle, from the early concept phase, through the test and validation phase. The authors will present the various development phases of the Renault 1.5 dCi passenger car diesel engine and will demonstrate the efficiencies and synergies that can be gained by using one modeling tool for multiple activities in the cycle, allowing hand-off of models between departments and scale-up/down of model fidelity as required for each particular task.