Mexican emission requirements for new vehicles and engines are adopted by the Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT). Emission compliance is generally required with either the US or European emission standards.
Emission and fuel regulations are published as Mexican standards—Norma Oficial Mexicana (NOM). Typically, the same NOM standard number covers a given vehicle category (for example, NOM-042 for light-duty vehicles or NOM-044 for heavy-duty diesel engines), with revisions indicated by the year of publication.
Regulated Engines and Vehicles
Emission regulated categories of engines and vehicles include:
- Light-duty vehicles (passenger cars and light commercial vehicles),
- Heavy-duty truck and bus engines, including engines fueled by diesel, gasoline and gaseous fuels.
In 2013, Mexico adopted CO2 emission and fuel economy regulations for light duty vehicles  that are harmonized with the US EPA standards for model year 2012-2016 vehicles and call for an average fuel economy of 14.9 km/L (35 mpg) in new vehicles by MY2016.