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Mexico NOM-163 Vehicle CO2 Standard

Mexico NOM-163 Vehicle CO2 Standard: Imposes fleet-average targets and compliance credit rules for new light-duty vehicles

Maílis Carrilho
Written by Maílis Carrilho
Updated on February 19th, 2026

Summary

NOM-163-SEMARNAT-SCFI-2023 regulates CO2 emissions from new light-duty vehicles through corporate fleet-average targets and defined calculation methodologies. Obligated OEMs and importers must compute observed vs target averages, retain auditable evidence, and manage compliance credits and transfers per the NOM appendices. Non-compliance can result in conformity assessment failure and market access restrictions. Strong data governance across testing, sales reporting, and credit accounting is essential.

Details

Jurisdictions
  • Mexico
Mandatory for

Mandatory for manufacturers/importers placing covered vehicles on the Mexican market within the scope (fuel types, weight classes, and model year definitions).

Exemptions

Exceptions/exclusions typically arise from:

vehicle categories outside scope (weight, use class, or fuels not covered),

special provisions for limited volume categories if specified by the NOM’s appendices,

transitional provisions linked to model-year implementation.

Deep dive

2 min read
Published Feb 19, 2026

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What’s Required

Obligated parties (typically OEMs and importers responsible for placing vehicles on the market) must implement compliance programs covering:

  • Fleet-average calculations: Calculate corporate average CO2 performance (observed vs target averages) using defined test procedures, vehicle attributes, and the standard’s methodology.

  • Reporting and evidence: Maintain auditable records supporting vehicle model data, test results, sales volumes, and calculation inputs needed for corporate averages. Regulators and authorised inspection/verification entities can require evidence during conformity assessment.

  • Credit generation and transfer rules: The standard includes mechanisms for compliance credits, and the 2023 version references appendices and mechanisms associated with compensation and credit transfers between corporate entities. Firms must document credit origin, eligibility, and transfer approvals.

  • Conformity assessment approach: Compliance is supported by the Mexican conformity assessment system, with accredited and approved inspection units determining compliance under procedures aligned to the Ley de Infraestructura de la Calidad and the NOM’s evaluation framework.

Operationally, manufacturers/importers need robust governance linking: product planning, homologation/testing, sales reporting, and compliance credit management.

Important Deadlines

  • Standard issued: NOM-163-SEMARNAT-SCFI-2023 is published and maintained in official NOM repositories.

  • Model year coverage: Official discussions around the NOM reference applicability through model year ranges (including references to vehicles with model years before 2028 in official DOF materials tied to the NOM’s development process).

Current Status

  • In force as the applicable federal NOM governing CO2 emissions performance for covered new vehicles, with official listings maintained on DOF/normalisation portals.

Penalties for Non-Compliance

Non-compliance can lead to:

  • conformity assessment failure and restrictions on marketing/commercialization for non-compliant vehicles,

  • administrative sanctions under the regulatory and normalisation enforcement system,

  • potential recalls or corrective actions, depending on enforcement findings and sector practice.

Examples of Known Violations

Common failure modes include:

  • incorrect or incomplete sales volume data affecting fleet averages,

  • credit accounting errors (double counting, invalid transfers),

  • documentation gaps for test evidence,

  • misclassification of vehicle variants to obtain more favorable targets.

Resources


Maílis Carrilho
Added by:
Maílis Carrilho
Sustainability Research Analyst
Maílis Carrilho is a Sustainability Research Analyst (Intern) at Net Zero Compare, contributing research and analysis on climate tech, carbon policies, and sustainable solutions. She supports the team in developing fact-based content and insights to help companies and readers navigate the evolving sustainability landscape.
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Added on Feb 19, 2026 by Maílis Carrilho ·