3. GRBP was informed about the activities of the Informal Working Group on Additional Sound Emission Provisions (IWG ASEP) (GRBP-75-38), of the Informal Working Group on Measurement Uncertainties (IWG MU) (GRBP-75-05) and of the Task Force on Vehicles’ Sound (TF VS) (GRBP-75-32).

4. The expert from IWG ASEP GRBP introduced a proposal that aimed to clarify the current wording of UN Regulation No. 51 (ECE/TRANS/WP.29/GRBP/2022/3). GRBP adopted the proposal, as amended by GRBP-75-36 and subject to deletion “or later” for the ISO standard references in Annexes 3 and 8, and requested the secretariat to submit it for consideration and vote at the June 2022 sessions of WP.29 and AC.1 as a new Supplement to the 03 series of amendments to UN Regulation No. 51.

5. GRBP also addressed another proposal by IWG ASEP that introduced Real Driving Additional Sound Emission Provisions (RD ASEP) as a preliminary test procedure for the purpose of collecting experience on the new test and evaluation concept. (ECE/TRANS/WP.29/GRBP/2022/4). GRBP adopted this proposal, as amended by GRBP-75-37, and requested the secretariat to submit it for consideration and vote at the June 2022 sessions of WP.29 and AC.1 as a new Supplement to the 03 series of amendments to UN Regulation No. 51.

6. The expert from Norway, in his capacity of Chair of IWG MU, presented proposals that introduced a temperature- and test-track compensation for vehicle noise (ECE/TRANS/WP.29/GRBP/2022/8). GRBP adopted the proposal, subject to the a correction of the equation for the mean value of logarithms of speeds vi in Annex 3, Appendix 3, paragraph 4.3. See the session report for the corrected formula.

7. GRBP requested the secretariat to submit the proposal for consideration and vote at the June 2022 sessions of WP.29 and AC.1 as a new Supplement to the 03 series of amendments to UN Regulation No. 51.

8. The expert of IWG MU proposed to align the entry into force of draft Supplements (GRBP-75-04-Rev.1). GRBP agreed to request WP.29 and AC.1 to postpone to their June 2022 sessions consideration of draft Supplement 7 to the 03 series of amendments to UN Regulation No. 51 (ECE/TRANS/WP.29/2022/4), in order to combine it into a consolidated proposal with the amendments mentioned in paragraphs 4, 5 and 7 above.

9. The expert from China proposed to extend the transitional period in paragraph 11.8. of the 03 series of amendments to UN Regulation No. 51, due to the difficulties in meeting the noise limits by microvans and micro-trucks available at the national market (GRBP-75-40 and GRBP-75-41). GRBP agreed to extend the transitional period until the end of 2023 and requested the secretariat to include this modification in draft Supplement 7 to the 03 series of amendments to UN Regulation No. 51 (paragraph 8 above). For any further extension, GRBP invited the expert from China to submit an official document to the next session.

10. The expert from IWG MU introduced a general approach how to handle measurement uncertainties (ECE/TRANS/WP.29/GRBP/2022/9, as amended by GRBP-75-07, and GRBP-75-08). GRBP endorsed this document and requested the secretariat to publish it as a document of reference on the GRBP website. The expert from IWG MU pointed out that an amendment to this document would be presented at the next session. GRBP that WP.29 should be informed about the developed general approach to measurement uncertainties, because it could apply to UN Regulations beyond the scope of GRBP.

11. The expert from IWG MU proposed to update their Terms of Reference (GRBP-75-06-Rev.1). GRBP adopted the revised Terms of Reference, as laid down in Annex II of the session report.

12. The experts from OICA reported on the outcome of three studies:

• Study on future sound limits values for type approval for vehicles of categories M and N (GRBP-75-16 and GRBP-75-17);
• Study on tyre performance (GRBP-75-18, GRBP-75-19-Rev.1 and GRBP-75-19-Rev.1-Add.1);
• Aggregation study with ETRTO on tyre performance (GRBP-75-20 and GRBP-75-21-Rev.1).