The RD-ASEP informal group met in February 2026 in Geneva. The Analysis Task Force requested additional data on hybrids, CVT transmissions, and battery electric vehicles. The Editing Task Force addressed copyright issues with UN and ISO Secretariats, determining that current document practices continue unchanged. The group clarified that RD-ASEP development focuses on measurement procedures for real driving conditions and noise emission limits under full and partial load, not establishing a new regulatory phase.

The RD-ASEP informal group met in Brussels. Officers and representatives from eleven contracting parties and four NGOs were present. The group discussed copyright approval requirements for UN website materials. A February 2026 meeting with UNECE and ISO secretariats will address incorporating third-party standards into UN regulations. The Data Analysis Task Force reported on ESE in ICE vehicles and data limitations. Discussions covered vehicle control ranges, CVT handling, and vehicle category applicability. An issues list was established for draft regulatory text. The next meeting is scheduled for April 14-16, 2026 in Berlin.

Proposal to supersede document GRBP/2026/4 intended to introduce a “default mode”, to specify requirements to be applied to the emission of Enhanced Exterior Sound (EES), with corresponding transitional provisions, and to draw a limit curve to introduce electric vehicles and hybrid electric vehicles that can be propelled without an internal combustion engine operating in the scope of ASEP (Annex 7).

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.

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-

IWG RD-ASEP status report to GRBP-83 after the 10th session in December 2025. Work on RD-ASEP for UN R51 is developing a mandatory procedure after the monitoring phase, while R41 work has concluded. The Data Analysis Task Force reported on database sufficiency, boundary conditions, CVT vehicle modelling, and potential inclusion of N₂/N₃/M₂/M₃ vehicles. An Editing Task Force created a consolidated R51.04 draft reviewed in December. IWG RD-ASEP recommends no monitoring requirements be approved without corresponding mechanisms to collect, analyze, and report results. M category/R51 informal document submission expected September 2026 and working document February 2027. L-category/R41 requires no further action.

IWG RD-ASEP is developing a mandatory procedure for UN R51 after the monitoring phase, with R41 work concluded. The Data Analysis Task Force reported in October 2025 on vehicle database sufficiency, boundary conditions, and CVT vehicle modeling. An Editing Task Force created a consolidated R51.04 draft reviewed in December 2025. IWG RD-ASEP recommends that no monitoring requirements be approved without corresponding mechanisms to collect, analyze, and report results. Submission targets shifted to September 2026 for informal document and February 2027 for working document due to database finalization and financial support needs.