Because of the rising demand for CO2 emission limits and the high cost of fuel, the electrification of heavy-duty vehicles has become a hot topic. Manufacturers have tried a variety of designs to entice customers, but the outcomes vary depending on the application and availability of recharging. Without affecting vehicle range, plug-in hybrids provide a potential for the automobile industry to reach its CO2 reduction objectives. However, the actual CO2 emission reductions will largely rely on the energy source, user behavior, and vehicle design. This research compares a series plug-in hybrid medium-duty truck against two baselines: nonhybrid and pure electric commercial trucks. As well as evaluating and contrasting the different tools to quantify CO2 emissions, this manuscript offers fresh information on how to simulate various powertrain components used in electrified vehicles. According to the findings, plug-in hybrids with batteries larger than 50 kWh can reduce emissions by 30%, while still meeting the 2030 well-to-wheel CO2 regulations. The recommended battery size for plug-in hybrid is 100 kWh, and for electric vehicles it is 320 kWh. The range of a plug-in hybrid is 18% longer than that of nonhybrid, 6% longer than that of a full hybrid, and 76% longer than that of a pure electric powertrain with a fully charged battery.