A novel transient drive cycle simulation software package (TSVSIM) has been developed and tested with a transient engine dynamometer. TSVSIM functions by analysing vehicle parameters using a standard vehicle model and implementing a control strategy for the duration of the vehicle test.The transient engine simulation technique can be used as a cost-effective approach for improving engine calibration and vehicle emission performance. A complete system is capable of producing modal and integral mass emissions data with accurate time resolution. It has particular advantages for the upcoming Federal and European emission legislation and associated extremely low emission limits.TSVSIM has been successfully applied to a number of vehicle and engine combinations and has been tested with a range of legislative and performance drive cycles. Results presented in the paper demonstrate good correlation with corresponding data obtained from a chassis rolls dynamometer system for both performance and emissions.