The Workshop to Identify Research Needs and Impacts in Predictive Simulation for Internal Combustion Engines (PreSICE), jointly sponsored by the Office of Basic Energy Sciences, Office of Science and the Vehicle Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, convened in March 2011. Over 60 U.S. leaders in the engine combustion field from industry, academia, and national laboratories gathered together to examine two critical areas of advanced simulation as identified by the U.S. automotive and engine industries. First, modern engines require precise control of the injection of a broad variety of fuels that is far more subtle than achievable to date and that can be obtained only through predictive modeling and simulation. Second, the simulation, understanding, and control of these stochastic in-cylinder combustion processes lie on the critical path to realizing more efficient engines with greater power density. A report, A Workshop to Identify Research Needs and Impacts in Predictive Simulation for Internal Combustion Engines (PreSICE), was generated as a result of this workshop and is now available.