This paper presents a simulation-based system-level evaluation of a four-source hybrid electric vehicle integrating a LiFePO4 battery, a PEMFC, a VIPV, and a compressed-air energy storage subsystem. A detailed MATLAB/Simulink model is developed using a common DC-bus architecture and four independent in-wheel hub motors with a total rated power of 12 kW. A rule-based energy management system is used to control how power is shared among different sources, maintain the battery's charge, and regulate the DC-bus voltage. The vehicle's performance is evaluated using the WLTP Class 2 driving cycle, and seven hybrid configurations are systematically compared under the same operating conditions. Simulation results confirm accurate tracking of the reference velocity profile and stable DC-bus regulation at 225 ± 3 V across all configurations. The measured specific energy consumption is approximately 5.05 kWh/100 km, including regenerative braking. Energy flow analysis shows that the battery provides short bursts of power and recovers energy from braking. In contrast, the fuel cell offers a consistent power source, which is especially useful for long-distance travel. With a 50 L hydrogen tank at 350 bar, the fuel cell extends the estimated driving range from about 95 km in battery-only operation to approximately 513 km. The integration of VIPV and compressed-air subsystems provides additional auxiliary contributions, increasing the total achievable range to roughly 606 km under full battery utilization, while improving current smoothing and transient load support. Parametric assessment of hydrogen and compressed-air storage systems reveals that hydrogen storage capacity is the principal determinant of operational duration, while compressed air provides only a modest increase in range, though it is useful for short-term support. These findings validate the technical viability of four-source hybridization and elucidate the complementary functions of electrochemical, photovoltaic, and pneumatic energy sources within a practical multi-motor vehicle framework.