Mexico: Heavy-Duty Engines
Diesel Engines
First emission standards for new heavy-duty diesel engines—applicable to vehicles of GVW > 3,857 kg—were established on 6 June 1988 and became effective in model year 1993 [NOM-044-ECOL-1993]. These standards were based on US 1991 and later requirements, including the applicable US EPA test methods. Since February 2003, engines can also meet European standards, as an alternative to the US EPA requirements.
New emission requirements for heavy-duty truck and bus engines were adopted in 2006, which required compliance with US 2004 or Euro IV equivalent standards effective July 2008 [2888]. In 2014, a proposal to skip over US 2007 and Euro V requirements and move directly to US 2010 or Euro VI was published [3536] but has not been finalized.
In 2018, emission standards were aligned with US 2010/Euro VI (the Mexican “B” standard) effective 2021.01, with a US 2007/Euro V (the Mexican “AA” standard) transition period [3812] but implementation was delayed due to concerns over the availability of ULSD. The first delay occurred 2020.11 when implementation was set to 2022.01. The second delay occurred 2021.11 when implementation was set to 2025.01. However, a judgement issued 2023.07 ordered that the agreement for the second delay be revoked and that the requirements of the 2018 version of the standard be enforced. While the government revoked the second delay in 2024.04, it did not issue clarification on the enforcement of the B standard [6319][6320]. This combined with the lack of full nationwide availability of ULSD has left the enforcement issue in considerable confusion.
The emission requirements are summarized in Table 1 [2888][2890][3812].
| Standard | Date | Requirements | |
|---|---|---|---|
| US EPA | European | ||
| - | 1993 | US 1991 | - |
| - | 1994 | US 1994 | - |
| - | 1998 | US 1998 | - |
| - | 2003.02 | US 1998 | Euro III |
| A | 2008.07 | US 2004 | Euro IV |
| AA | 2019.07a | US 2007c | Euro V |
| B | 2021.01b,d | US 2010 | Euro VI |
| a Standard allowed from January 1, 2019 b Standard allowed from January 1, 2019, but only come into force when there is full availability of 15 ppm S diesel fuel c NOx limit of 1.2 g/bhp-hr (FTP) d Enforcement unclear, see discussion | |||
Gasoline & Gas Engines
Emission standards for new heavy-duty engines fueled by gasoline, LPG, natural gas and other alterative fuels are specified by the NOM-076 standard adopted in 1995 [2891] with later amendments [2889]. Similar to the diesel regulations, the emission standards are applicable to gas engines used in vehicles of GVW > 3,857 kg.
Gasoline and gaseous fueled engines are tested over the FTP transient test and must meet the US EPA-based emission standards shown in Table 2. Natural gas engines can alternatively be tested over the European ETC test and meet the Euro IV/V-based emission standards shown in Table 3.
| Standard | Date | GVW | HC | NMHC | CO | NOx | HCev* |
|---|---|---|---|---|---|---|---|
| kg | g/bhp-hr | g/test | |||||
| A | 1998 | 3,857 - 6,350 | 1.1 | - | 14.4 | 4.0 | 3.0 |
| > 6,350 | 1.9 | - | 37.1 | 4.0 | 3.0 | ||
| B | a | 3,857 - 6,350 | - | 0.14 | 14.4 | 0.2 | 1.75 |
| > 6,350 | - | 0.14 | 14.4 | 0.2 | 2.30 | ||
|
* Evaporative emissions limit applicable to gasoline and LPG vehicles only. a 18 months after official publication of a notice of full nationwide availability of regular gasoline (Magna) of 30 ppm average and 80 ppm maximum sulfur content. | |||||||
| Standard | Date | CH4 | NMHC | CO | NOx | PM |
|---|---|---|---|---|---|---|
| g/kWh | ||||||
| A | 2013.02 | 1.10 | 0.55 | 4.00 | 3.50 | - |
| B | 2014.07 | 1.10 | 0.55 | 4.00 | 2.0 | 0.03 |
Manufacturers may choose to certify gasoline and gaseous fueled vehicles with GVW up to 6,356 kg on a chassis dynamometer over the FTP-75 cycle. Table 4 summarizes emission standards for chassis-certified vehicles.
| Standard | Date | GVW | NMHC | CO | NOx | HCev* |
|---|---|---|---|---|---|---|
| kg | g/km | g/test | ||||
| A | 2013.02 | 3,857 - 4,536 | 0.285 | 3.418 | 0.807 | 3.0 |
| 4,537 - 6,356 | 0.372 | 4.350 | 1.243 | 3.0 | ||
| B | a | 3,857 - 4,536 | 0.121 | 3.977 | 0.124 | 1.75 |
| 4,537 - 6,356 | 0.142 | 4.536 | 0.248 | 2.30 | ||
|
* Evaporative emissions limit applicable to gasoline and LPG vehicles only. a 18 months after official publication of a notice of full nationwide availability of regular gasoline (Magna) of 30 ppm average and 80 ppm maximum sulfur content. | ||||||
From model year 2013, gasoline, LPG and natural gas vehicles of GVW ≤ 6,356 kg should be equipped with “OBD II or similar” onboard diagnostic system.