An integrated vehicle system simulation has been developed to take advantage of advances in physical process and component models, flexibility of graphical programming environments (such as MATLAB-SIMULINK), and ever increasing capabilities of engineering workstations. A comprehensive, transient model of the multi-cylinder engine is linked with models of the torque converter, transmission, transfer case and differentials. The engine model is based on linking the appropriate number of single-cylinder modules, with the latter being thermodynamic models of the in-cylinder processes with built-in physical sub-models and transient capabilities to ensure high fidelity predictions. Either point mass or multi-body vehicle dynamics models can be coupled with the powertrain module to produce the ground vehicle simulation. The integrated simulation can be used for predictions of dynamic response and performance of engine and driveline systems, for assessment of alternative system configurations and for integration studies in conjunction with the rest of the components of ground vehicles. Various illustrative studies are conducted for heavy-duty truck vehicles to demonstrate the capability of the simulation to predict performance and transient system response.