The subgroup on UN R51 and UN R138 met on 14 January 2026 to review comments on outcome documents. Switzerland’s sentence in 3.5. was retained for clarification. JASIC’s definition of EES footnote was changed to reference GRB-68-03. Transitional provisions remained unchanged with a new item added for Annex 1, Appendix 1. Agreement was reached on 6 dB allowance in Annex 7 paragraph 3.4. and 3 dB for three specific cases. A draft paragraph for GRB-68-03 justification will be submitted by email. Switzerland’s proposal SG-13-05-2025-07-30 will serve as basis. GRBP-82-39 includes examples for active systems generating EES and creation of part B for electric vehicles. Work on RD-

Proposal to amend GRBP/2026/4. Amendments to UN Regulation No. 51 include updates to the Table of Symbols in paragraph 2.24; new definitions for Active Sound Source, Enhanced Exterior Sound (EES), and Vehicle Master Control Switch; specifications for EES operation requiring driver intentional action and default deactivation; sound limits complying with UN-Regulation No. 138 below 20 km/h and this Regulation from 20 to 80 km/h; transitional provisions allowing extension of existing approvals for 24 months; modifications to Annex 7 control ranges, anchor points, and slope calculations for electrically propelled vehicles; and updates to Annex 1 and Annex 3 regarding EES systems. GRB-68-03 commitment to add EES guidance document is confirmed.