The Emission Control Capability of Catalyst-Equipped Vehicles at Extended Mileages Under Field Conditions

The emissions performance of a fleet of five vehicles equipped with prototype 1975 catalyst emission control systems and run under field conditions for up to 125,000 miles (202,000 km) was evaluated. The vehicles were driven by non-expert drivers in California and Michigan for commuting and personal use and maintained in a manner similar to in-use vehicles. The average fleet emissions of hydrocarbons (HC) remained below the 1975 California emission standards appropriate for these vehicles for 80,000 miles (129,000 km), the average carbon monoxide (CO) emissions remained below the standard for 70,000 miles (113,000 km), and emissions of oxides of nitrogen (NOx) never exceeded the appropriate standards.