5. The expert from the Informal Working Group on Measurement Uncertainties (IWG MU) presented their final report (GRBP-79-02) and a draft document for reference (ECE/TRANS/WP.29/GRBP/2024/8 and GRBP-79-48-Rev.1). During an in-depth discussion, several experts from contracting parties expressed concerns about the formal adoption of the document for reference and its legal status. They pointed out that the document could be misinterpreted as being legally binding and modifying the established sound limits in UN Regulation No. 51. In the absence of consensus, GRBP postponed the discussion to the next session.

6. GRBP took note of the status report of IWG RD-ASEP (GRBP-79-11).

7. The expert from OICA presented a proposal with corrections and clarifications on the power definition, calibration, temperature correction and reference sound assessment (GRBP-79-33-Rev.1). Subject to deletion of the second occurrence of double paragraph 2.8., GRBP adopted the proposal and requested the secretariat to submit it for consideration and vote at the June 2024 sessions of WP.29 and AC.1 as draft Supplement 10 to the 03 series of amendments to UN Regulation No. 51.

8. The expert from OICA proposed to extend the ASEP provisions from annex 7 of the 03 series of amendments to UN Regulation No. 51 to electric vehicles (GRBP-79-43). GRBP invited its experts to provide comments to OICA, with the aim of continuing discussion at the next session, based on an official document.

9. The expert from OICA presented an interim report on the ongoing ASEP/ RD-ASEP study (GRBP-79-45) which included a first set of data on RD-ASEP monitoring according to the 03 series of amendments to UN Regulation No. 51. GRBP noted the low response rate and encouraged all type approval authorities and technical services of contracting parties applying UN Regulation No. 51 to transmit the relevant data, as a sufficient number of datasets are needed to conduct a good study. In reply to a question from the expert of EC, the expert of OICA indicated that they would need around 1,000 data sets to conduct a good study on RD-ASEP. The expert from OICA also clarified that only an excel data sheet should be transmitted, without a pdf report.