RME views: Vehicles were on the road before UN R155 came into force. Retrofitting extends vehicle life in line with climate action and circular economy objectives. Retrofitters must be responsible only for components involved in the transformation and any parts they add or modify, not for original vehicle components. A risk management demonstration dossier limited to the transformed system must be included in transformation approval applications. If the origin vehicle is not R155-approved, retrofitters may provide the dossier without laboratory tests. If R155-approved, authorities decide on compliance, requiring laboratory tests if needed. Manufacturers’ data are not accessible to retrofitters. The application of cyber security provisions (i.e., UN R155 compliance) should be delayed by two years from the entry-into-force of the new regulation for the approval of EC/HFCV retrofit systems and revisions to UN R155 should also provide two-year transitional provisions before the application to the retrofit regulation.

Proposal to add an Abbreviations section, redefine scope to apply to electric powertrain retrofit systems for M₁–M₃ and N₁–N₃ vehicle categories intended to be transformed into pure electric vehicles (EV) or Hydrogen Fuel Cell Vehicles (HFCV), replace “conversion” terminology with “transformation” throughout, separate requirements into distinct annexes for EVs and HFCVs, add a Provisions for PTI section specifying retrofit system identifiability and certificate requirements, insert transitional dates for REESS compliance with UN Regulation 100 (31 August 2027 onwards for new types; 31 August 2029 onwards for all types), insert transitional dates for braking compliance with UN Regulation 13 (31 August 2026–2029 for new types; 31 August 2028–2031 for all types) and UN Regulation 13-H (31 August 2028 for new types; 31 August 2030 for all types), add mass distribution verification requirements when unladen weight variation exceeds 5%, and align mass and dimensions procedures with regional requirements such as EU 2021/535.