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Emission Standards

United States: California: Light-Duty Vehicles: GHG Emissions

2009-2016 Standards

In 2002, California adopted Bill AB 1493, known as the Pavley legislation, that required the California Air Resources Board (CARB) to implement regulations to control emissions of greenhouse gases (GHG) from motor vehicles in California. The regulation was developed by CARB in 2004, and became effective from 1 January 2006.

The standards phased-in over the period of 2009 to 2016, Table 1. The average GHG reduction from new California cars and light trucks was about 22% in 2012 and about 30% in 2016, compared to model year 2004 vehicles.

Table 1
California fleet average GHG emission standards
Time FrameYearGHG Standard, g CO2/mi (g CO2/km)CAFE Equivalent, mpg (l/100 km)
Near Term 2009323 (201)439 (274)27.6 (8.52)20.3 (11.59)
2010301 (188)420 (262)29.6 (7.95)21.2 (11.10)
2011267 (166)390 (243)33.3 (7.06)22.8 (10.32)
2012233 (145)361 (225)38.2 (6.16)24.7 (9.52)
Medium Term 2013227 (142)355 (221)39.2 (6.00)25.1 (9.37)
2014222 (138)350 (218)40.1 (5.87)25.4 (9.26)
2015213 (133)341 (213)41.8 (5.63)26.1 (9.01)
2016205 (128)332 (207)43.4 (5.42)26.8 (8.78)

The GHG standards were incorporated into the California low emission vehicle (LEV) legislation. There were two fleet average GHG requirements: (1) for passenger car/light-duty truck 1 (PC/LDT1) category, including passenger cars and light-duty trucks below 3,750 lbs equivalent test weight (ETW); and (2) for light-duty truck 2 (LDT2) category, including light trucks between 3,751 lbs ETW and 8,500 lbs gross vehicle weight (GVW). In addition, medium-duty passenger vehicles (MDPVs) from 8,500 to 10,000 lbs GVW were included in the LDT2 category for GHG emission standards.

The GHG standards were defined in grams per mile of CO2-equivalent emissions (g CO2/mi in Table 1), calculated from the following formula:

CO2-Equivalent = CO2 + 296 × N2O + 23 × CH4 - AC Allowances

Manufacturers were allowed to use N2O = 0.006 g/mi in lieu of measuring N2O exhaust emissions. The AC emission allowances were determined based on the design of the air conditioning system, with higher allowances for more leak-free and energy-efficient systems. Two sets of CO2 values were determined: (1) city values measured over the FTP test, and (2) highway values over the HWFET cycle. In the calculation of average emission for a manufacturer, the city values were taken with a weight factor of 55%, and the highway values with a weight of 45%. Additional adjustment factors and special methods were used for calculation in vehicles fueled by alternative fuels and in ZEV vehicles.

2017-2025 Standards

In January 2012, CARB approved GHG emission regulations for MY 2017-2025 light-duty vehicles. The regulations were part of the part of the “Advanced Clean Car Rules” that also included the LEV III emission standards for criteria air pollutants and ZEV regulations [2946].

The GHG emission regulation was aligned with the federal 2017-2025 GHG emissions and fuel economy proposal by the EPA/NHTSA. When the federal MY 2017-2025 GHG regulation became finalized, in August 2012, CARB adopted regulatory provisions to the effect that vehicles meeting federal GHG emission standards for MY 2017-2025 are “deemed to comply” with California standards. This approach provided manufacturers a convenient option to comply with one set of rules nationwide.