This paper presents the results of engine and vehicle simulation modeling for a wide variety of individual technologies and technology packages applied to two medium-duty vocational vehicles. Simulation modeling was first conducted on one diesel and two gasoline medium-duty engines. Engine technologies were then applied to the baseline engines. The resulting fuel consumption maps were run over a range of vehicle duty cycles and payloads in the vehicle simulation model. Results were reported for both individual engine technologies and combinations or packages of technologies. Two vehicles, a Kenworth T270 box delivery truck and a Ford F-650 tow truck were evaluated. Once the baseline vehicle models were developed, vehicle technologies were added. As with the medium-duty engines, vehicle simulation results were reported for both individual technologies and for combinations. Vehicle technologies were evaluated only with the baseline 2019 diesel medium-duty engine.The vehicle technology combinations in the T270 delivery truck yielded from 1% to 12% fuel savings, averaged over all the duty cycles. Fuel savings for the diesel engine technology packages ranged from 1% to 5%, averaged over all the duty cycles. The simulation of gasoline engine technology packages produced from 6% to 9% and 6% to 10% for the V-6 and V-8 engines, respectively. The benefits of individual technologies vary widely depending on the drive cycles.