Fuel cell technologies are gaining relevance as a sustainable solution for heavy-duty transportation; however, further studies are still required to assess their performance and durability under realistic operating conditions. In this context, the EU is developing a VECTO-compatible certification methodology to evaluate energy consumption and driving range of hybrid heavy-duty vehicles. This framework will enable accurate differentiation of fuel cell vehicles, supporting targeted incentives and accelerating their deployment in the segment responsible for the largest share of freight-related CO₂ emissions. This work presents a sensitivity analysis of ageing effects in a low-temperature PEM fuel cell system operating under VECTO driving cycles, addressing the challenge of quantitatively evaluating fuel cell degradation following the new standards for heavy-duty vehicle applications. A dynamic fuel cell system model, validated under both steady-state and transient conditions, is employed to realistically reproduce the behavior of a real vehicle [2]. The model incorporates a semi-empirical degradation model calibrated using experimental data, accounting for the influence of operating conditions such as low and high load operation, start-stop events, and system dynamics on voltage degradation, and is applied to a 5-LH FCEV truck using an energy management strategy based on Pontryagin’s Minimum Principle (PMP). The results demonstrate that both control strategies and dynamic operating constraints have a significant impact on fuel cell ageing under VECTO Long Haul and Regional Delivery cycles, for reference and low payload conditions. These findings contribute to a more robust and quantitative assessment of ageing effects in heavy-duty fuel cell vehicles, providing valuable insights for the design of degradation-aware energy management strategies, the definition of certification-relevant operating constraints, and the development of future VECTO-based methodologies that explicitly account for durability considerations alongside efficiency.