We present the creation and assessment of ordered hexagonal donut nanoplates (O-HDP) derived from a Pt2FeCu/C ternary alloy, which serve as a highly effective cathode catalyst for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs). The catalyst was produced using a surfactant-free molten-salt technique and was verified by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses for its ordered face-centered tetragonal lattice with a unique donut-like shape. The electrochemical tests showed an activity increase of nearly 17 times compared to Pt/C, while maintaining stability for up to 50k potential cycles. In the single-cell PEMFC evaluations under H-2/O-2 conditions, the O-HDP Pt2FeCu/C reached a peak power density of 1.711 W cm(-2) at a current density of 3.98 A cm(-2) and retained 91% of its maximum performance after 30000 durability cycles. The exceptional activity and long-term stability were attributed to its ordered atomic structure, reduced Pt-Pt spacing, distinctive structural geometry, and synergistic alloying effects, making it a promising candidate for future PEMFC applications. Additionally, the simulation of a PEMFC stack using Matlab/Simscape under the urban dynamometer driving schedule (UDDS) driving cycle successfully replicated the realistic dynamic voltage (380-500 V), power (55-60 kW), and thermal responses, confirming the model's validity as a replacement for the unavailable hardware. The interconnected electrochemical and thermal behaviors highlighted the importance of thermal management to sustain the stack efficiency and longevity in changing the automotive conditions.