Light-duty vehicles are defined as vehicles of GVW ≤ 3857 kg. Passenger cars (PC) are defined as vehicles with up to 10 seats, including the driver. Light trucks are classified in four groups—corresponding 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
Model Year 1993-2003
First emission standards for both light- and heavy-duty vehicles were established on 6 June 1988 and became effective in model year 1993 [NOM-044-ECOL-1993]. The standards were based on the US regulations and test methods (FTP-75). The 1993 requirements were based on the US 1981 emission standards.
The light-duty standards were later strengthened, effective 2001 [NOM-042-ECOL-1999]. The 2001 requirements represent the US Tier 1 standards without OBD II provisions.
These emission standards are summarized in Table 1. 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 diesels. Natural gas and LPG vehicles have the same standards as gasoline vehicles.
|Light Trucks CL1|
|Light Trucks CL2|
|Light Trucks CL3|
|Light Trucks CL4|
|* total hydrocarbons (THC) prior to model-year 2001
† diesel vehicles only
Gasoline, natural gas, and LPG vehicles of all classes and all model years must also meet an evaporative (SHED) limit of 2 g/test.
Model Year 2004 and Later
The model year 2004 and later standards are based on US Tier 1 and Tier 2 standards and Euro 3 and Euro 4 limits . New vehicles must meet the standards set out in either Table 2 (based on US Tier 1/2 limits) or Table 3 (based on Euro 3/4 limits). Vehicles meeting these standards are also required to be equipped with OBD.
|CL Class 1|
|CL Class 2||2.26||0.80||0.162||0.72||0.125||0.65||0.070|
|CL Class 3||2.83||0.95||0.200||0.86||0.137||0.78||0.100|
|CL Class 1|
|CL Class 2||1.81||0.63||0.13||0.39||0.10||0.33||0.040|
|CL Class 3||2.27||0.74||0.16||0.46||0.11||0.39||0.060|
Notes to Table 2 and Table 3:
- Emission durability requirements:
- 80,000 km / 50,000 mi for US EPA option (Table 2), or
- 100,000 km for European option (Table 3)
- 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.
An important factor in the phase-in of these vehicles is the introduction of gasoline with 30 ppm average and 80 ppm maximum sulfur, and diesel fuel with 15 ppm sulfur. The calendar year that these fuels become available nationally is referred to as “Year 1” (Año 1). It was expected to be 2009, according to Mexican fuel quality regulations , but the deadline has not been met. Vehicles meeting the “A” standard in Table 2 are those produced between 2004 to 2009. Vehicles meeting “B” standard in Table 2 and Table 3 are those produced from 2007 to “Year 3”—2 calendar years after “Year 1”. Vehicles meeting “C” standard in in Table 2 and Table 3 are those produced starting in “Year 1”. The phase-in schedules for vehicles meeting B and C standards are laid out in Table 4 and Table 5, respectively.
|Standard||Year 1||Year 2||Year 3||Year 4|
While the standards in Table 2 and Table 3 are based on US EPA limits and European limits, they are not necessarily structured the same way. For example, the NOx and PM limits defined by the “A” standard in Table 2 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 NOx standards decrease to limits based on 50,000 mile US EPA Tier 2 values. The NOx 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 in Table 3 are equivalent to Euro 3 and 4 limits. Note the different durability requirements for the standards in Table 2 (80,000 km) and Table 3 (100,000 km).