Technical Standards

Light-Duty Vehicle Classification

Light-duty vehicles are defined as vehicles of Gross Vehicle Weight (GVW) ≤ 3857 kg. Passenger cars (PC) are defined as vehicles with up to 10 seats, including the driver. Light trucks are classified into four groups—corresponding approximately to the US Light Duty Truck 1 to 4—based on the GVW and the test weight (weight of the vehicle with full fuel tank) as follows:

• CL1: GVW ≤ 2722 kg, test weight ≤ 1701 kg
• CL2: GVW ≤ 2722 kg, test weight 1701 – 2608 kg
• CL3: GVW 2722 – 3857 kg, test weight ≤ 2608 kg
• CL4: GVW 2722 – 3857 kg, test weight 2608 – 3857 kg

Weight ratings based on the European grouping for passenger cars and light commercial vehicles using a vehicle’s reference mass (weight of vehicle with full tank of fuel + 100 kg) are also used:

• CL Class 1: reference mass ≤ 1305 kg
• CL Class 2: reference mass > 1305 kg but ≤ 1760 kg
• CL Class 3: reference mass > 1760 kg

MY 1993-2003

Emission standards for light-duty vehicles (MY 1993-2003) are summarized in the table below. The standards were based on US regulations and Federal Test Procedures (FTP) (FTP-75). The 1993 requirements were based on the US 1981 emission standards, while the 2001 requirements represent the US Tier 1 standards without On Board Diagnostics (OBD) II provisions.

The standards apply both to gasoline and diesel vehicles, with the exception of NOx standards, as specified, and the PM standard that applies only to diesel vehicles. Natural gas and liquefied petroleum gas (LPG) vehicles have the same standards as gasoline vehicles.

Gasoline, natural gas, and LPG vehicles of all classes and all model years must also meet an evaporative (SHED) limit of 2 g/test.

MY 2004 and later

Limit Values

New vehicles must meet either the standards based on US EPA standards or those based on Euro standards, as outlined in the tables below. Tailpipe emissions limits for model year 2004 and later vehicles are based on US Tier 1 and Tier 2 limits and Euro 3 and Euro 4 standards. The evaporative emissions standard is set at 2.0 grams per test for all gasoline and LPG vehicles, under any standard or regulatory option. Vehicles meeting these standards are also required to be equipped with OBD, with European, U.S. or any similar OBD systems allowed. Gasoline vehicle standards also apply to natural gas and LPG vehicles.

Gasoline, natural gas, and LPG vehicles of all classes and all model years must also meet an evaporative (SHED) limit of 2 g/test.

Gasoline, natural gas, and LPG vehicles of all classes and all model years must also meet an evaporative (SHED) limit of 2 g/test.

Equivalence with US and European Standards

Light-duty vehicle tailpipe emissions limits for the US option are based on a combination of US Tier 1 and Tier 2 limit values for 50,000 miles of durability. The evaporative emissions limit is based on the substantially less stringent European limit.

Light-duty vehicle emission limits for the European standards option are based on a combination of Euro 3 and Euro 4 standards. The evaporative emissions limit matches Euro 3 and 4 standards.

Emission durability requirements

While the standards are based on US EPA limits and European limits, they are not necessarily structured the same way. For example, the NO_x and PM limits defined by the “A” standard are a combination of 50,000 mile and full useful life US EPA Tier 1 limits. For the “B” and “C” standards, the PM limits do not change, (i.e., they stay at the Tier 1 limits) while the NO_x standards decrease to limits based on 50,000 mile US EPA Tier 2 values. The NO_x limit for the “B” standard is US Tier 2 Bin 10 and for the “C” standard is Bin 7 (for lighter vehicles) and Bin 9 (for heavier vehicles). With the exception of “B” standard for gasoline, LPG and natural gas, the standards are equivalent to Euro 3 and 4 limits. While the US Tier 1 and Tier 2 regulations set durability requirements of 100,000 miles, the regulation in Mexico sets durability requirements of 50,000 miles (80,000 km) for the US EPA option, and 100,000 km for the European option.

Phase-in schedule

The phase-in schedule for NOM 042 is dependent on the year of nationwide compliance with low sulfur fuel standards. At the time of publication of the current standard the rule quality standard has still not been finalized. “Year 1” was defined as the “time when the relevant regulatory instrument establishes full availability in the country of gasoline with an average fuel sulfur content of 30 ppm and a maximum of 80 ppm and diesel with a maximum of 10 ppm sulfur content.” With the continued delay in implementation of the existing fuel quality standards, “Year 1” of the calendar is still not set.

Compliance with “A” standard was a requirement or option for vehicles with model years 2004 to 2009. Compliance with “B” standard was phased in beginning with model year 2007 and will be phased out after the model year produced in “Year 3” of full compliance with the fuel quality standard. Compliance with “C” standard will be phased in starting with the first year of full compliance with the fuel quality standard and will be mandatory for all vehicles in the forth year of full compliance. The phase-in schedules for vehicles meeting B and C standards are as follows:

Fuel quality requirements

An important factor in the phase-in of these vehicles is the introduction of low sulfur gasoline and diesel. NOM-016-CRE-2016 set gasoline sulfur limits at an average of 30 ppm and a maximum of 80 ppm and set a timeline for diesel to meet 15 ppm sulfur limits by 2019 nationwide. According to that standards, “Year 1” (Año 1) will be 2019 and full compliance with Standard C would not be achieved until 2023.