UN R51 specifies that conditioning of a silencing system is necessary only in cases where exhaust gases come into contact with silencer fibrous materials. This proposal would apply the same concept in L category noise regulations.

Proposal to clarify the test procedure by explicitly excluding first gear where possible from the ASEP control range.

Overview of discussions for the future development of vehicle noise regulations prepared by the GRB secretariat.

Based on the outcomes of a European Commission study, proposal to clarify the text and align its provisions with other vehicle sound regulations, especially UN R41, including to replace references to “two wheeled moped” with the term “L1 category vehicles” (and consequently to replace references to “moped” with “vehicle”) and to replace the term “noise” with “sound” (except for references to background noise) throughout the regulation.