4. The expert from Norway, in his capacity of Chair of the Informal Working Group on Measurement Uncertainties (IWG MU), reported on the progress of IWG MU (GRBP-74-20) and proposed to update its Terms of Reference (GRBP-74-12). GRBP adopted the revised Terms of Reference, as laid down in Annex II.

5. The expert from IWG MU presented a proposal which reduces measurement uncertainties for the ambient conditions, vehicle selections and preparations (ECE/TRANS/WP.29/GRBP/2021/22). GRBP adopted the proposal, subject to the following correction of paragraph 2.1.3.2.2. of Annex 3: “Tests carried out on request of the manufacturer at air temperatures below 5° C shall be accepted as well”. GRBP requested the secretariat to submit it for consideration and vote at the March 2022 sessions of WP.29 and AC.1 as draft Supplement 7 to 03 series of amendments to UN Regulation No. 51.

6. The expert from IWG MU briefly introduced a second package of draft amendments to UN Regulation No. 51 (GRBP-74-13). GRBP also noted an updated reference document with a general approach to estimate measurement uncertainties (GRBP-74-11) and was of the view that this document could be applicable to UN Regulations beyond the scope of GRBP.

7. The expert from OICA presented the final report of the tyre performance study undertaken by the European Automobile Manufacturers’ Association (ACEA) (GRBP-74-08 and GRBP-74-09). He also presented the outcome of another study on the future sound limits for type approval of vehicles of categories M and N (GRBP-74-27) and pointed out that the final report would be presented to GRBP next year. GRBP agreed to come back to the study in the future and invited experts to directly contact OICA with questions or comments on the study.

8. On behalf of the Informal Working Group on Additional Sound Emission Provisions (IWG ASEP), the expert from Germany reported on their activities (GRBP-74-21) and introduced an updated draft new 04 series of amendments to UN Regulation No. 51 (GRBP-74-22). The Chair invited GRBP experts to study this draft and to provide comments to IWG ASEP.

9. GRBP noted that the Taskforce on Sound Level Limits (TF SL) would be referred to as “Task Force on Vehicle Sound” (TF VS). GRBP noted a TF SL progress report (GRBP-74-39) and draft guidelines (GRBP-74-03-Rev.1) and deferred consideration to the next session.