The study focuses on enhancing the durability of polymer electrolyte fuel cells (PEFCs) for heavy-duty vehicles through the evaluation of degradation rates of key components. By utilizing a combination of electrochemical characterization and synchrotron X-ray radiography, the research proposes a method to simultaneously assess the degradation of proton exchange membranes (PEMs), catalyst layers (CLs), and gas diffusion layers (GDLs). Findings from accelerated stress tests indicate that water saturation serves as a crucial degradation indicator for GDLs, showcasing degradation in parallel with PEM and CL components. The article highlights the importance of studying the durability of GDLs in fuel cell applications for heavy-duty vehicles, shedding light on the need for further research in this area. Additionally, the research offers insights on prioritizing components within membrane electrode assemblies (MEAs) for replacement in case of fuel cell stack degradation in fuel cell electric vehicles (FCEVs). Overall, the study contributes valuable knowledge to the field of material science and fuel cell technology, emphasizing the significance of improving the longevity and performance of PEFCs for future transportation advancements.