13. GRPE reviewed the letter sent by the expert from Malta (GRPE-76-17). GRPE noted the statements of some delegations informing GRPE that they faced similar requests in the past and reporting that no evidence was provided that could convince of the environmental benefits of such retrofitted systems. GRPE noted also the need to verify the safety performance of such systems as the risk caused by the presence of hydrogen onboard of road vehicle is not insignificant. Experts from the automotive industry stated that they had reviewed the performance of such systems and that, due to the regulatory pressure on the industry concerning the CO2 performance of their products, they would have introduced such technologies on their vehicles, if the benefits would have been demonstrated. They also noted that hydrogen cause damage to the materials used in engines and that the retrofitting such systems on existing vehicles not foreseen for the use on hydrogen could pose durability issues. GRPE requested the secretariat to note in the session report that GRPE has not received sufficient evidences of benefits from these systems to start regulatory activities. GRPE expressed the idea that any country willing to approve such system on the national basis may wish to take into consideration the usual emission tests (Types I, II, III, and IV), low temperature tests, the durability (including Type V) and OBD provisions.