Progress in the Development of Tier 2 Light-Duty Diesel Vehicles

The U.S. Environmental Protection Agency (U.S. EPA) has been conducting a test program to evaluate efforts to bring light-duty diesel vehicles into compliance with U.S. Federal Tier 2 Light-duty Emission Standards. Between April 2002 and October 2003, five advanced prototype light-duty diesel vehicles equipped with NOx adsorption catalysts, PM-traps, and diesel oxidation catalysts were tested at the U.S. EPA's National Vehicle and Fuel Emission Laboratory (NVFEL). The vehicle testing was conducted using low sulfur (<15 ppm) diesel fuel. All of the tested vehicles demonstrated the considerable progress recently made by vehicle manufacturers and systems integrators in applying advanced NOx and PM emission control technology to light duty diesel vehicles in anticipation of the U.S. Light-duty Tier 2 emission standards. PM emissions for all of the vehicles were well below the Tier 2 Bin-5 emission levels. The most recently tested vehicle demonstrated intermediate-useful life (50,000 miles) PM, NOx, and NMHC emissions at or below the Tier 2 Bin-5 levels. This paper represents an early survey of emissions from the first generation of prototype clean diesel vehicles.