A powertrain simulation model to translate the demands of a vehicle driving schedule into an engine RPM/torque versus time trajectory is developed. The formulation of a time density matrix in the speed/load plane of the engine allows a rational approach to the selection of dynamometer test points for emission control strategy development, fuel economy improvement and/or component development and evaluation. Steady-state engine dynamometer data combined with the results of the powertrain model can be used to project emissions and fuel economy values for an entire drive cycle such as CVS-Hot. This provides the development engineer with a powerful tool to make preliminary assessments of the potential of various control strategies or intended component modifications without the necessity of building a complete vehicle prototype. It also provides the basic building block for optimizing emission control strategy to meet required constraints with maximum fuel economy. Limited comparisons between actual vehicle tests and powertrain projections show good agreement in trends.