The paper presents the fuel economy and performance capabilities of a switchable P2/P3 Hybrid Transmission for commercial and military use cases through modeling and simulation. An overview of the simulation model developed to analyze the vehicle performance and fuel consumption for a specified drive cycle is presented. The model includes the key components of the electrified powertrain including engine, hybrid transmission, electric motor and battery. Use cases were identified to represent Commercial vocational applications and military analogues. The results of P2/P3 Hybrid Powertrain model simulation are compared with that obtained from a model of baseline Conventional Torque Converter Automatic Transmission (AT). The comparison is made for both vehicle performance and fuel economy, and the results indicate that the P2/P3 Hybrid Transmission demonstrates better fuel economy with same or better performance than the baseline heavy-duty automatic transmission. Opportunities to achieve further improvements in fuel savings with the P2/P3 Hybrid Transmission are also identified.