Version of the proposed 03 series of amendments to UN R51 based on GRB/2012/2 (consolidated version of the O3 series as agreed by GRB to date) but incorporating further improvements as proposed in GRB-54-05 and GRB-54-06 from the previous GRB session.

Version of the proposed 03 series of amendments to UN R51 that consolidates the latest changes agreed within GRB (GRB/2005/2/Rev.2, all “method B” amendments, including WP.29/2011/64, and the Additional Sound Emission Provisions (ASEP)).

This proposal would revise the transitional provisions of the proposed 03 series of amendments to Regulation No. 51 (see GRB/2012/2). OICA believes the preceding text may create problems in the granting or accepting of type approvals under the previous series.

Proposal of transitional provisions for the 03 series of UN R51 on vehicle noise. Importantly, the proposal seeks to address the handling of transitions and extensions between the 02 and 03 series, perhaps offering a template for transitional provisions in general.

Consolidated version of the proposed 03 series of amendments to UN R51, including OICA remarks on updating references to Annex 9 and concerning the Annex 2 qualification of the vehicle to be tested in each instance.

OICA submission proposing to align the current stationary vehicle noise emission measurement provisions of UN R51 with those in the latest draft international standard ISO/DIS 362.

Table prepared by OICA highlighting various elements in the consideration of noise in UN Regulation Nos. 9, 28, 41, 51, 59, 63, 92, and 117.

Text prepared by the International Organization of Motor Vehicle Manufacturers (OICA) in order to introduce the concept of “revision of approvals” in the regulations under GRB responsibility.

The transitional provisions in GRB/2012/08 are not in line with the latest UN Guidelines on Transitional Provisions. This proposal updates the transitional provisions and adds two amendments specifically applicable for UN Regulation No. 51.

List of acronyms and abbreviations contained in Regulation No. 51 prepared by the International Organization of Motor Vehicle Manufacturers (OICA).

This document presents the OICA position on vehicle classification, limits and dates in UN Regulation No. 51.03 (draft consolidated version presented in document GRB/2012/8).

Text prepared by the International Organization of Motor Vehicle Manufacturers (OICA) in order to incorporate the latest stage of relevant ISO standards in UN Regulation No. 51, Revision 2.

Proposal from the International Organization of Vehicle Manufacturers to update the requirements on the noise test track to the latest stage of the applicable standards (from ISO 19844:1994 (i.e. Annex 8 of this Regulation) to ISO 10844:2011) and to incorporate transitional provisions to allow repaving of non-compliant test tracks to the ISO 10844:2011 standards.

Proposal from the International Organization of Vehicle Manufacturers (OICA) to update requirements for the noise test track from ISO 19844:1994 (i.e. Annex 8 of this Regulation) to ISO 10844:2011 and to allow for repaving of existing, non-compliant test tracks to meet the ISO 10844:2011 standards.

Proposal to clarify the wording of the 03 series of amendments to UN R51 as adopted by the World Forum in June 2015 (document WP.29/2015/62). The adopted wording could lead to the interpretation that sound levels measured on the left side of the vehicle are mixed by calculation with sound levels measured on the right side of the vehicle. The proposed new wording clarifies that the overall sound emission is assessed individually per vehicle side.

Presentation of issues raised during discussions of the GRE Task Force on EMC requirements with regard to the application of several UN Regulations to trolley buses depending upon their configuration (e.g., dual-mode operation either connected to overhead cables or in standard bus mode).

OICA comments on the ISO proposals to clarify the provisions of Regulation No. 51, Revision 3, Annex 7.

OICA proposal to provide a clearer and more precise definition for “stable acceleration”. The definition introduced in document GRB/2017/02 is specified as "when the acceleration from line AA’ to PP’ has a low variation to the acceleration from line PP’ to BB’.” The term “low variation” is imprecise and so OICA proposes the wording “when the acceleration ratio a_{(PP’-BB’)}/a_{(AA’-BB’)} is lower than 1,2.”

Discussion of current issues related to vehicle noise levels, especially given the availability of affordable electronic devices that enable car owners to artificially increase vehicle sound output.

1. Paragraph 1: The scope was originally drafted for the Annex 3 test which refers to normal urban driving. A proposed additional sentence covers the intention of Annex 7.
2. Paragraph 2.8.1.: Adopt the wording from standard ISO 362-1:2015 for clarity. If an electric motor is not operational during the type approval tests, then its power must not contribute to the calculation of the power to mass ratio (PMR).

3. Paragraph 2.24., table: Amendments regarding paragraph 2.2.7.4. of Annex 3 because paragraph 2.2.7.4. is new. Amendments also for line BB’ to reflect that the measurement will not end after line BB’. For the speeds vAA’, vBB’ and vPP’, a wrong reference coming from ISO was corrected.

4. Paragraph 2.27.: A new definition of “kickdown” was introduced since this term is used in this Regulation. With a large variety of products, it is unclear what “kickdown” exactly means. This definition is a design neutral approach and reflects the intention of Annex 3 and Annex 7.
5. Paragraph 2.28.: Prevention of downshift is a legal measure to ensure that the vehicle can be tested within the test conditions as specified by this Regulation.
6. Paragraph 3.3.: Deletion of meaningless sentence given the requirement that the vehicles have to be loaded in order to be able to achieve the urban driving conditions as described in paragraph 3.1.2.2. of Annex 3. The sentence has similarly already been deleted in Regulation (EU) No. 540/2014.
7. Paragraph 6.2.3.: The current specification requires a hybrid vehicle to be assessed according to the additional sound emission provisions (ASEP), even though such a vehicle does not have the internal combustion engine running within the control range of Annex 7. There will be no valid test result. Such vehicles should be exempted from ASEP.
8. Annex 1, Appendix 1: For the test method according to 3.1.2.1 the pre-acceleration length may differ per gear ratio. In this case, it is necessary to report the pre-acceleration length per gear ratio.
10. Annex 1, Appendix 2 : Missing elements of the information document have been added, namely “0.2. type” and “3.2.6. pressure charger(s)”.
11. Annex 3, paragraph 2.1.: Lower temperatures will lead to slightly higher test results due to an increased tyre rolling sound. Thus, testing at lower temperatures will be a disadvantage for the manufacturer. If for practical reasons the manufacturer wishes to carry out tests at lower temperatures, this shall be accepted by the type approval authority.
12. Annex 3, paragraph 2.2.1.: For M1 and N1, the current provision has led to ambiguities about its meaning. The proposed new sentence clarifies the meaning. Further, the tolerances are broadened, as research shows, that the impact of the test mass can be neglected in a wide range. For M2, M3, N2 and N3, the current provision has led to ambiguities about its meaning. The proposed new sentence clarifies the meaning. If the test mass of the vehicle is equal to the target mass, the target mass shall be achieved with a tolerance of ±5 per cent according to equation (2) in paragraph 2.2.7.1. of Annex 3. Consequently this has to be valid also for the test mass mt. If the test mass of the vehicle is lower than the target mass according to equation (12) and (13) in paragraph 2.2.7.1. of Annex 3, the test mass shall be achieved with a tolerance of ±5 per cent. Concerning M2 and M3, for clarification and to avoid misunderstanding, the loading conditions for complete vehicles of category M2 (M > 3,500 kg) and M3 were aligned with the requirements for incomplete vehicles of category M2 (M > 3,500 kg) and M3. As a consequence, vehicles of category M2 (M ≤ 3,500 kg) have to be added to the table and their test mass requirement has to be aligned with those of vehicles of category M1 and N1.
13. Annex 3, paragraph 2.2.7.1.: See the above justification for M2, M3, N2 and N3 in paragraph 2.2.1.
14. Annex 3, paragraph 2.2.7.4.: If a manufacturer does not produce vehicles with two axles only, he is not able to calculate the right test mass for his vehicles with more than two axles. For calculating the test mass, a vehicle with two axles has to be put on a scale to measure the unladen front axle load, mfa load unladen, and the unladen rear axle load, mra load unladen, for being able to calculate munladen as given in formula (3) of paragraph 2.2.7.1. of Annex 3. In addition, a new paragraph provides a procedure for calculating the test mass of a virtual vehicles with two axles, based on an existing vehicle with more than two axles, when a vehicle with two axles is physically not available to be put on a scale.
15. Annex 3, paragraph 3.1.2.1.: Proposal to extend the measurement to a position where misfiring is detectable. A redundant sentence is deleted per paragraph 2.2.4.
16. Annex 3, paragraph 1.1.2.1.4.1.(d): Clarify gear usage where one gear ratio is above 2 m/s² and the other below a_urban.
17. Annex 3, paragraph 1.1.2.1.4.1. (e): The suggested changes clarify the proper setup for testing for vehicles with very short gear ratios.
18. Annex 3, paragraph 3.1.2.1.4.3.: Introduction of specifications for vehicles with only one gear ratio.
19. Annex 3, paragraph 3.1.2.1.5. : Simplify testing. With a fixed vehicle length, it is not necessary to adjust the test equipment (light barriers, pylons) for each vehicle.
20. Annex 3, paragraph 3.2.3.: Reference correction
21. Annex 3, paragraph 3.2.5.3.: Reference correction
22. Annex 4, paragraph 1.: The performance of the fibrous material can be checked by completely removing the fibrous material. This reintroduces an option removed when Annex 5 of the 02 series of amendments was revised.


23. Annex 6, paragraph 2.1.: Proposal to simplify and clarify CoP. During the conformity of production procedures, neither the vehicle nor tyres will have a proper preconditioning. In many cases, the vehicles are foiled and parts may be missing as theft protection. It is very unlikely that the vehicles will have already the same performance as the type approval vehicle. This provision adopts the specifications from the revised ASEP provisions (Informal document GRB-65-26, Annex 7, para. 1). In addition, the range of masses was broadened in the same way as proposed for type approval.
24. Annex 6, paragraph 3.: Reference correction.

Consolidation of draft amendments collected by OICA from various sources, including remarks of contracting parties during expert group meetings and meetings, and from discussions within the informal working group on ASEP. The document has been prepared to encourage discussion.

UN R51 allows the use mechanical or electronic devices to control the gear shifting and measures to avoid accelerations greater than 2.0 m/s². However, the measures are not defined and the manufacturer or technical service is not obliged to document the methodology in the test report. This proposal would introduce a table with examples for devices and measures for reference and would require documentation of methodology used.

UN R51 allows the use mechanical or electronic devices to control the gear shifting and measures to avoid accelerations greater than 2.0 m/s². However, the measures are not defined and the manufacturer or technical service is not obliged to document the methodology in the test report. This proposal would introduce a table with examples for devices and measures for reference and would require documentation of methodology used.

OICA presentation on modeling, including tire rolling noise and power train noise, of vehicle sound emissions and compliance with UN R51 requirements.

Pursuant to the GRB-67 discussions, OICA proposes to restrict the application of the partial load driving to pure electric vehicles in order to facilitate adoption of document GRB/2018/2 while allowing the ASEP informal group to further consider the proposed formulas for the ASEP anchor point.

OICA discussion paper as further developed by the ASEP informal group on interpretation of the provision “The sound emission of the vehicle under typical on-road driving conditions, which are different from those under which the type-approval test set out in Annex 3 and Annex 7 was carried out, shall not deviate from the test result in a significant manner.”

Proposal to clarify that the gear ratio i+1 by definition has an acceleration (not an “engine speed”) lower than gear ratio i.

Proposal for amendments to the draft Supplement 6 to the 03 series of amendments submitting clarifications to the text from the ASEP II informal group.

Purpose of study was to specify any potential improvement or deterioration of noise performance in light of the other parameters and to provide the necessary information regarding the possible additional tightening of the limits, without undermining the overall balance that has to take into account also other performances.

Proposal to specify that Supplement 7 does not apply to type approvals issued prior to its entry-into-force.

Proposal to clarify the details of the data-handling during the monitoring phase required in paragraph 5.1.1.

This proposal concerns to amendments to Annex 7. The proposed changes regarding sound enhancement systems are based on the 03 series of amendment up to Supplement 9. In addition, some clarifications concerning power definition and temperature correction have been included based on experiences with the last changes of this regulation.

In introducing ASEP in Annex 7 in 2016, the scope was limited to vehicles with internal combustion engines (ICE) based on the experience of variabilities in the exhaust silencing systems. Electric driven vehicles have been exempted from ASEP. For electric driven vehicles the new UN Regulation No. 138, dealing with the reduced audibility of these vehicles, was worked out until 2017. At that moment no one expected sound enhancement systems beyond the scope and aim of UN R138.

This proposal is an approach to address the concern that electric vehicles might be equipped with sound enhancement systems beyond the scope and aim of UN R138. This proposal does not require any changes to UN R138.01. This proposal is given as a supplement to enable the quickest entry into force, providing all manufacturers clear direction on the design of sound enhancement systems.

Some corrections and clarifications concerning power definition, calibration, temperature correction and Reference sound assessment

Technical Background Information to Supplement 11 to UN R51.03

The text reproduced below was prepared by the experts from OICA in order to address the original intent of the Task Force on Quiet Road Transport Vehicles (TF QRTV). This proposes to expand the speed range of ASEP forBEVs down to speeds > 0 km/h.

Proposal to replace references to UN GTR 21 by its type-approval equivalent UN R177, provide transitional provisions pursuant to amendments introduced in Supplements 10 and 11, and clarify calibration provisions and procedure for system check (cf: ISO 362).

Proposal to cover all types of electric vehicles (xEVs) in the provisions of ASEP (Annex 7) in UN Regulation No. 51.

This proposal concerns primarily amendments to Annex 7 of UN Regulation No. 51. The proposed changes are based on the 03 series of amendment to UN Regulation No. 51 up to Supplement 10.

Informal consolidated text for better reading.

Proposal replaces document GRBP/2025/20

Supplement 7 introduced an inconsistency in R51.03 Annex 8. As currently
written, it requires free-rolling tyre noise testing to be conducted in
accordance with both ISO 362-3:2016 and Annex 3, Appendix 3

Proposal to make a correction to the procedure of free rolling tyre noise testing described in Annex 8.

By this proposal all types of electric vehicles (xEVs) are included in the provisions of ASEP (Annex 7) in UN Regulation No. 51. If applicable, input of the dedicated subgroup of IWG RD-ASEP has been incorporated.

Proposal to replace references to GTR 21 by references to UN R177.

Proposal to address electric vehicle enhanced sound issues in the short term until the new 04 series of amendments enters into force.

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).

Consolidation in Supplement 11 includes: clarification of Verification/Adjustment and editorial corrections with transitional provisions (GRBP/2025/20 with GRBP-82-07); correction of Tyre Road Sound Measurement for Indoor-Testing (GRBP-82-22); introduction of ASEP in Annex 7 for BEVs and HEVs (GRBP/2026/4 with GRBP-83-xx); update of ISO standards in Annex 3 and Annex 8 (GRBP/2026/5 with GRBP-83-xx); and reference for Power Definition regarding new UN R177 (GRBP/2026/13). The consolidated version of Supplement 11 is to be submitted to the 199th WP.29 in June.