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UN R179 Supplement 1 (00 series) · UNECE Regulation No. 179 (ECE R179) — Laboratory Measurement of Brake Emissions for Light-Duty Vehicles.

UN R179 — Supplement 1 to the 00 series of amendments

Base text → Supplement 1

Adopted at the WP.29 199th sessionEntry into force not yet known
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What changed
  • In Annex 5, vehicles of categories X and Y must be tested in the ADS testing mode of UN Regulation No. 154, extended where necessary.
  • A “Category M1 vehicle” now has not more than nine seats, instead of eight seats in addition to the driver's seat.
  • “User-selectable mode” replaces “Driver-selectable mode”, and new definitions cover the “ADS user” and the “vehicle user”.
Why
  • The changes are required to incorporate vehicles with Automated Driving Systems into the existing Regulation.
  • Driver related definitions might not be applicable in the case of vehicles equipped with an ADS.
  • “User-selectable mode” includes ADS users who can change vehicle conditions which affect the non-friction braking capability of a vehicle.

Q1What changed19 changes

ADS testing mode in the reference method (Annex 5, para. 3.)

Vehicles of categories X and Y must be tested using the ADS testing mode of UN Regulation No. 154. This mode is set out in paragraph 2.4.2.7. of Annex B6 to that Regulation. Where necessary, this mode is extended to enable the correct execution of the tests. If the vehicle has an ADS testing mode, it must be engaged for all operation on the chassis dynamometer where an ADS feature is active. The text on external sensors for the brake torque now comes after these new sentences, with the same words.

The vehicle-specific friction braking share coefficient shall be determined applying the WLTP-Brake cycle on a fully UN Regulation No. 154 compliant chassis dynamometer. All brakes shall be equipped with external sensors to determine the brake torque at each of the wheels. Alternatives and acceptance criteria are described in paragraph 5 of this annex.
Vehicles of categories X and Y shall be tested using the ADS testing mode as set out in paragraph 2.4.2.7. of Annex B6 to UN Regulation No. 154, but extended to enable the correct execution of the tests, where necessary.
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Category M1 vehicle and mass in running order (paras 3.1.1. and 3.1.4.)

A “Category M1 vehicle” means a vehicle used for the carriage of passengers and comprising not more than nine seats. Before, the limit was eight seats in addition to the driver's seat. For vehicles of categories X and Y, the mass in running order must not include the mass of the driver.

"Category M1 vehicle" means a vehicle used for the carriage of passengers and comprising not more than eight nine seats in addition to the driver's seat.
"Mass in running order" is the mass of the vehicle, with its fuel tank(s) filled to at least 90 per cent of its capacity, including the mass of the driver, fuel, and liquids, fitted with the standard equipment in accordance with the manufacturer's specifications and, when they are fitted, the mass of the bodywork, the cabin, the coupling and the spare wheel(s) as well as the tools. For vehicles of categories X and Y the mass of the driver shall not be included.

Service brake and brake calliper definitions (paras 3.3.3. and 3.3.8.)

The “service brake” definition now says “the driver or the ADS” instead of “the driver”. The “brake calliper” definition now says “brake input” instead of “driver brake pedal input”.

"Service brake" means the (friction or non-friction) braking system allowing the driver or the ADS to control, directly or indirectly and in a graduated manner, the speed of a vehicle during normal driving or to bring the vehicle to a halt (standstill).
"Brake calliper" means a mechanical device that converts driver brake pedal input into a clamping force on the brake pads to generate braking torque.

User-selectable mode, ADS user and vehicle user (paras 3.7.18. to 3.7.18.2.)

The defined term “Driver-selectable mode” becomes “User-selectable mode”. Before, it referred to a distinct driver-selectable condition. Now it refers to a distinct vehicle user selectable condition that can affect the non-friction braking capability of a vehicle. New paragraph 3.7.18.1. defines “ADS user” as a human user of an Automated Driving System, as defined in UN Regulation No. [ADS]. New paragraph 3.7.18.2. defines “Vehicle user” as a driver or ADS user. Paragraph 12.10. of Annex 1 and paragraphs 4.1. and 4.5. of Annex 5 now say “user-selectable” instead of “driver-selectable”.

"Driver-selectable User-selectable mode" in the context of this Regulation refers to a distinct driver-selectable vehicle user selectable condition that can affect the non-friction braking capability of a vehicle.
"ADS user" means a human user of an Automated Driving System, as defined in UN Regulation No. [ADS].
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New R.E.3 footnote and ADS abbreviation (para. 1. and Table 1)

A new footnote refers to the Consolidated Resolution on the Construction of Vehicles (R.E.3.), document ECE/TRANS/WP.29/78/Rev.8. Paragraph 1. and paragraph 3.1.4. carry calls to this footnote. Table 1 has a new abbreviation: ADS, Automated Driving System.

As defined in the Consolidated Resolution on the Construction of Vehicles (R.E.3.), document ECE/TRANS/WP.29/78/Rev.8, https://unece.org/transport/vehicle-regulations/wp29/resolutions
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Q2Why it changed

Proposed by
Task Force on Automated Vehicles Regulations Screening (AVRS)
Working party
GRPE, 94th session (March 2026)

Reasons

  • The document introduces changes required to incorporate vehicles with Automated Driving Systems into the existing Regulation.

    Source
    “The document introduces changes required to incorporate vehicles with Automated Driving Systems into the existing Regulation.”

  • References to the Consolidated Resolution on the Construction of Vehicles (R.E.3.) are updated to include ADS equipped vehicles in the scope. Vehicle categories X and Y are introduced in Revision 8 of R.E.3. These vehicles are not capable to be driven manually above 6 km/h.

    Sources (2)
    “References to the Consolidated Resolution on the Construction of Vehicles (R.E.3.) are updated to include ADS equipped vehicles in the scope.”
    “Vehicle categories X and Y are introduced in Revision 8 of R.E.3, prepared by the Task Force on Automated Vehicle Categorisation (TF-AVC) under GRSG and GRVA, and are not capable to be driven manually above 6 km/h.”

  • Driver related definitions might not be applicable in the case of vehicles equipped with an ADS. Vehicles of categories X and Y might not have a driver or driver’s seat. Therefore the definition of Category M1 was changed according to the text of R.E.3 Rev.8. The mass of the driver should not be included into the mass in running order. The “service brake” and “brake calliper” definitions were generalised to include ADS as a source of brake input.

    Sources (4)
    “Driver related definitions might not be applicable in the case of vehicles equipped with an ADS”
    “Clarifications include vehicles of categories X and Y, which might not have a driver or driver’s seat, therefore definition of Category M1 was changed according to the text of R.E.3 Rev.8.”
    “Additionally, the mass of the driver should not be included into the mass in running order.”
    “Similarly, “service brake” and “brake calliper” definitions were generalised to include ADS as a source of brake input.”

  • “Driver-selectable mode” was changed to “user-selectable mode” to include ADS users. ADS users can change vehicle conditions which affect the non-friction braking capability of a vehicle.

    Source
    ““Driver-selectable mode” was changed to “user-selectable mode” to include ADS users who can change vehicle conditions which affect the non-friction braking capability of a vehicle.”

  • Vehicles equipped with an ADS were incorporated into the existing provisions on the “Reference Method and Calculation”. This addresses their testing through the “ADS testing mode” defined in UN Regulation No. 154.

    Source
    “Vehicles equipped with an ADS were incorporated into the existing provisions in paragraph 3. “Reference Method and Calculation” to address their testing via the “ADS testing mode” defined in UN Regulation No. 154.”

Document trail

  1. 2026-01ProposalECE/TRANS/WP.29/GRPE/2026/25Proposal by the Task Force on Automated Vehicles Regulations Screening (AVRS)
  2. —RevisedGRPE-94-35Text by the experts from the Task Force AVRS that amended the proposal
  3. —Working party adoptsECE/TRANS/WP.29/GRPE/94GRPE session report, para. 54
  4. 2026-04Sent to WP.29ECE/TRANS/WP.29/2026/156Text that GRPE sent to WP.29 and AC.1
  5. 2026-06-24WP.29 adoptsECE/TRANS/WP.29/1192Adopted at the 199th session (session report, para. 103)
  6. PendingIn forceDate not yet known

Q3Who is affected

Vehicle manufacturer

  • Prepare vehicles of categories X and Y for testing in the ADS testing mode, extended where necessary.
  • Make sure a fitted ADS testing mode can be engaged for all dynamometer operation where an ADS feature is active.
  • For categories X and Y, exclude the driver mass from the mass in running order (para. 3.1.4.).

Component supplier

  • No direct action for this role.

Technical service / Approval authority

  • Be ready to test vehicles of categories X and Y in the ADS testing mode, extended where necessary.

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ⓘ This report gives advice only. It is not legal or type-approval advice.

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