Proposal to add para. 4.4.1. through 4.4.8. to restructure target operation conditions provisions, add para. 4.4.7. to permit acceptance of runs outside the control range under specified provisions, modify para. 3.6.1. to change reference acceleration determination from maximum to selected acceleration for a selected reference v-t-e ratio, modify para. 4.5.4.1. to set negative calculated acceleration values to zero, add heading “Carry-over parameters from Annex 3” to para. 2.2.1.2., add para. 2.2.1.2.1. and 2.2.1.2.2., and modify constant speed test parameters to report vehicle speed vBB’_CRS_ANCHOR rather than reference speed vTEST of 50 km/h.

Task Force Data Analysis held an online meeting on 7 July 2026. The group discussed database analysis, including insufficient data for higher performance and acceleration, and agreed that more data are needed. When new data are generated, operation conditions should focus on higher performances covering the ASEP range, higher accelerations up to and exceeding 5 m/s, pass-by runs with gear shifting, and low speed measurements in the UN R117 AVAS control range. The group reviewed proposals to the TF-Editing based on draft UN R51.04 and agreed some changes, with review results to be uploaded as Rev.1. A question regarding the phrase “but no more than 2.0 m/s” in paragraph 3.1.2.1.4.3 regarding vehicles with only one gear ratio was noted as issue #23 pending further review.

This presentation, intended for discussion within TF Data Analysis RD-ASEP and not for conclusions, analyzes model performance using L_exp data from Annex_9_test_runs where both left and right sound were measured. Model performance varies across speed bins, with higher mean absolute error at low and high speeds. Adjusting theta_tr values improves mean absolute error across all speed bins. Testing without an envelope function results in more measurements exceeding expected values, requiring extra margins.

The agenda includes welcoming participants, reviewing and adopting the agenda, scheduling next meetings on 7th July and 24th August 2026, analyzing database distance in dB from the borderline, discussing proposals to TF-Editing based on draft UN R51.04 from the June Gothenburg session, preparing wording proposals for items 13–19 from the issues list, and reviewing decisions and work for the next meeting before reporting to IWG RD-ASEP.

This document presents a clean draft proposal for the 04 series of amendments to UN R51 (Noise of M₁–M₃ and N₁–N₃ Categories of Vehicles). The proposal establishes uniform provisions for sound emission approval of motor vehicles with at least four wheels, introducing comprehensive specifications for measuring vehicle noise during motion and stationary conditions. Key provisions include detailed test methods with outdoor and indoor testing options, sound level limits varying by vehicle category and power characteristics, requirements for vehicles of categories M₁ and N₁ to comply with Real Driving Additional Sound Emission Provisions (RD-ASEP), specifications for exhaust silencing systems containing fibrous materials, conformity of production procedures, and specific adaptations for vehicles equipped with Automated Driving Systems. The regulation applies from its official entry into force, with a transitional period allowing acceptance of prior-series approvals until a specified date.

IWG RD-ASEP is developing a mandatory test to assess compliance with paragraph 6.2.3 of Regulation 51.04 main body, assuring vehicle noise emission at speed, load, or acceleration conditions other than Annex 3 condition is linked to vehicle physics with no noise emission test detection or defeat device schemes. After the 13th session in June 2026, the Editing Task Force created a consolidated R51.04 draft incorporating R51.03 Supplements up to Supplement 11, with mandatory random RD-ASEP testing for approval and revised control range. Submission targets include informal document first draft September 2026, second draft February 2027, and expected working document for adoption February 2028.

The Task Force Data Analysis held 14 meetings, with 12 used to eliminate database errors and 2 to begin data analysis. The analysis revealed the need to better understand the concept and history of RD-ASEP development. Questions were raised regarding whether RD-ASEP should follow envelope functions framing typical sound behaviour of vehicle components or average behaviour with acceptable tolerance. Comparing databases from 2017/2020 and 2023/2024 showed different pass/fail rates across vehicle types. The group seeks clarification on RD-ASEP model optimization, accuracy expectations, and documentation explaining historical background and parameter selection.

Proposal to insert paragraphs establishing references to Software Identification Number definitions in Consolidated Resolution R.E.3 Annex 7 para. 2, insert paragraphs requiring manufacturers to provide Technical Services with information on hardware and software influencing performance, insert paragraphs allowing vehicle manufacturers to apply for new approvals to differentiate software versions for registered vehicles from those for new vehicles with duplication of tests avoided where possible, amend production discontinuation provisions to clarify that production is not considered definitively discontinued if manufacturers intend to obtain subsequent extensions for software updates of registered vehicles, and amend approval communications to include additional information regarding software identification and software updates in UN Regulations 51, 64, 138, 141, 142 and 165, as presented in document GRBP-83-36 and implementing Revision 8 to Consolidated Resolution No. 3 (WP.29/2025/147).

This document provides guidance for interpreting paragraph 6.2.3 of UN R51.03 concerning Additional Sound Emission Provisions for vehicles of category M₁ and N₁. Part A clarifies that typical on-road driving means driving at speeds between 15–100 km/h with accelerations not exceeding 2 m/s² and vehicle performance not exceeding 35 m/s, across any gear except reverse at engine speeds of at least 1.5 times idle speed and not exceeding the maximum specified in Annex 7. Significant deviation is defined as a sound level exceeding the reference value by at least 6 dB(A). Type approval test results derive from Annex 3 or Annex 7, with reference values determined using regression curves for Slope-Assessment or calculation principles for Lurban-Assessment. Part B addresses electric and hybrid vehicles when electrically propelled, extending ASEP scope under Supplement 11, applying comparable principles with modifications regarding active sound enhancement systems and operating speed ranges between 20–100 km/h for electric vehicles.

The agenda includes discussion of Terms of Reference from GRBP-78-13, procedural update from GRB-68-03, Analysis Task Force Report, Editing Task Force Report, R51.04 Issues List Review, draft R51.04 text review, Inside and Outside Boundary Condition discussions, and confirmation of next meeting date and place as August 31–September 1 in Geneva, Switzerland.

Current RD-ASEP derives the regulatory level based on the certified value without accounting for margin against regulatory values of the certified value. RD-ASEP additionally regulates partial acceleration, unlike current ASEP which only stipulates full-throttle acceleration. It is proposed that RD-ASEP should take into account a margin against the regulatory values of the certification values, similar to current ASEP, to prevent quiet vehicles such as BEVs from being unfairly deemed NG.

In vehicles with automatic transmissions, upshifts during testing cause SEM expected values to be exceeded. The proposal addresses three cases: vehicles with non-locked gear ratios, vehicles with locked gear ratios, and vehicles with only one gear ratio. For Case 1, such data does not meet conditions in R51-03 Annex 9 “4.5.2. Non-locked transmissions” and require no SEM correction. For Case 2, the proposal adds text to Annex 9 (7), Appendix 1, paragraphs 3.4. and 3.5., permitting substitution of maximum engine speed nMAX(AA-BB)TEST for nBBTEST when the maximum engine speed between AA’ and BB’ exceeds the engine speed at BB’.

The agenda includes a review of the schedule with next meetings on 7th July and 24th August, continuation of database analysis presentation from RDW, review of decisions and work for the next meeting, report to IWG RD-ASEP.

This presentation analyzes RD-ASEP model performance using test run data from Annex_9_test_runs where both left and right sound were measured. Current model shows 1.3% of measurements above L_exp; without the 2 dB margin this increases to 8.4%. Model overestimates at low speeds and underestimates at higher accelerations. Tyre rolling sound parameters have most influence on results and dominate most of the data set. Optimizing all 13 parameters reduces mean absolute error from 2.1 to 1.1 dB. More high acceleration measurements are needed to reliably calibrate the dynamic component.

Task Force Data Analysis (Sub Group to IWG RD-ASEP) held its 13th meeting on Wednesday, 3rd June 2026. The group reviewed database analysis including statistical analysis of differences between expected and measured sound levels, sub-model construction, and optimization calculations for parameter tables. Discussion addressed model construction concerns, vehicle failure differentiation, and data collection requirements including approval values according to UN R117. Next meetings are scheduled for Tuesday, 7th July and Monday, 24th August 2026.