Model Year 1987-2003 Model year 1988-2003 US federal (EPA) and 1987-2003 California (ARB) emission standards for heavy-duty diesel truck and bus engines are summarized in the following tables. Applicable to the 1994 and following year standards, sulfur content in the certification fuel has been reduced to 500 ppm wt. Table 1 EPA Emission Standards for Heavy-Duty Diesel Engines, g/bhp·hr Year HC CO NOx PM Heavy-Duty Diesel Truck Engines 1988 1.3 15.5 10.7 0.60 1990 1.3 15.5 6.0 0.60 1991 1.3 15.5 5.0 0.25 1994 1.3 15.5 5.0 0.10 1998 1.3 15.5 4.0 0.10 Urban Bus Engines 1991 1.3 15.5 5.0 0.25 1993 1.3 15.5 5.0 0.10 1994 1.3 15.5 5.0 0.07 1996 1.3 15.5 5.0 0.05* 1998 1.3 15.5 4.0 0.05* * - in-use PM standard 0.07

Table 2 California Emission Standards for Heavy-Duty Diesel Engines, g/bhp·hr Year HC HC CO NOx PM Heavy-Duty Diesel Truck Enginess 1987 - 1.3 15.5 6.0 0.60 1991 1.2 1.3 15.5 5.0 0.25 1994 1.2 1.3 15.5 5.0 0.10 Urban Bus Engines 1991 1.2 1.3 15.5 5.0 0.10 1994 1.2 1.3 15.5 5.0 0.07 1996 1.2 1.3 15.5 4.0 0.05 * - in-use PM standard 0.07

Useful Life and Warranty Periods Compliance with emission standards has to be demonstrated over the useful life of the engine, which was adopted as follows (federal & California): • LHDDE - 8 years/110,000 miles (whichever occurs first) • MHDDE - 8 years/185,000 miles • HHDDE - 8 years/290,000 miles Federal useful life requirements were later increased to 10 years, with no change to the above mileage numbers, for the urban bus PM standard (1994+) and for the NOx standard (1998+). The emission warranty period is 5 years/100,000 miles (5 years/100,000 miles/3,000 hours in California), but no less than the basic mechanical warranty for the engine family. Clean Fuel Fleet Program Table 3 shows a voluntary Clean Fuel Fleet (CFF) emission standard. It is a federal standard that applies to 1998-2003 model year engines, both CI and SI, over 8,500 lbs GVWR. In addition to the CFF standard, vehicles must meet applicable conventional standards for other pollutants.

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