## 4 Discussion
### Limitations  
While this study presents a systematic and efficient methodology for selecting critical test scenarios for autonomous vehicles, a few limitations remain that warrant further exploration. First, while the weighting system for the WCS calculation provides flexibility, the assignment of weights remains an area for further investigation. The default weights used in this study were based on expert judgement and case-specific adjustments; however, amore data-driven approach (e.g., machine learning optimization) could further enhance this process. Future studies could explore tuning these weights dynamically based on historical scenario relevance or real-world testing data. Second, this study focuses on scenario filtering without delving deeply into the execution or evaluation of the filtered test scenarios. While this work emphasizes safety-critical selection, future research could aim to verify the real-world safety impact of the chosen scenarios using experimental trials or high-fidelity simulations. Additionally, the integration of reinforcement learning or other adaptive scenario generation techniques, as explored in prior studies, could further enhance the coverage of safety-critical ODDs. Third, the scope of the scenario database may not fully capture rare edge cases or extreme environmental conditions (e.g., adverse weather, low visibility). These long-tail scenarios are critical for robust safety validation. Expanding the database to include such variables, along with performance feedback and incident data from real-world deployments, could enhance coverage and relevance. Fourth, although the validation conducted in this study successfully matched a significant portion of the selected scenarios with relevant test applications, expanding validation efforts to a larger variety of autonomous functionalities and real-world deployment cases would provide more generalized insights into the effectiveness of the methodology. Finally, the methodology is grounded in European and international regulatory frameworks (e.g., UNECE, EuroNCAP, ISO), which may limit its direct applicability in regions with different approval standards. In the future, it may be worthwhile to examine whether the proposed methodology could also be applied in countries where the typical type approval procedure is not in place (e.g., the United States). However, in order to establish a properly standardized test case catalogue, it is essential that the given country has existing regulations whose test cases can serve as a baseline. Nevertheless, we believe that the test plans developed from the regulations we applied could serve as a solid starting point in such countries as well, since many of the included scenarios address generally critical situations. Conceptualization, B.T. and Z.S. ; methodology, B.T. ; software, B.T. ; validation, B.T. ; formal analysis, B.T. ; investigation, B.T. and Z.S. ; resources, B.T. ; data curation, B.T. and Z.S. ; writing--original draft preparation, B.T. ; writing--review and editing, B.T. and Z.S. ; visualization, B.T. ; supervision, Z.S. ; project administration, B.T. ; funding acquisition, B.T. All authors have read and agreed to the published version of the manuscript. This research was implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development, and Innovation Fund, financed under the KDP-2021 funding scheme. Not applicable. Restrictions apply to the availability of these data. Data were obtained from TUV Rheinland-KTI Ltd. and are available from Balint Toth with the permission of TUV Rheinland-KTI Ltd. The authors are grateful to TUV Rheinland-KTI Ltd. for providing resources, including personnel, and access to relevant testing documents and databases. During the preparation of this manuscript, the authors used TUV-GPT-4o Bot for the purpose of checking the language for grammatical mistakes and clarity. The authors have reviewed and edited the output and take full responsibility for the content of this publication.