Heavy-duty vehicles represent one of the largest sources of NOx emissions and fuel consumption in North America. Used for drayage and the goods movement, approximately 70% of heavy-duty trucks on the road fall into this classification. CE-CERT has conducted a number of studies to evaluate advanced technology vehicles using its heavy-duty chassis dynamometer. This facility has been utilized to test yard tractors and hybrid vehicles for applications for the Ports of Los Angeles and Long Beach. During these studies, CE-CERT performed conventional vs. hybrid comparisons while managing the state of charge of the hybrid system. CE-CERT has also preformed research on the development of uniform test procedures for evaluating advanced technology vehicles for the Ports. In addition we have also utilized this facility for testing of natural gas buses and refuse haulers for the CEC, CARB, and SCAQMD and for a fleet of diesel vehicles for the SCAQMD.