The College of Engineering-Center for Environmental Research and Technology at the University of California, Riverside and Honda Motor Company are conducting a cooperative research program to study the emission characteristics and evaluate the environmental impact of advanced technology vehicles designed to have emission rates at, or below, the California ULEV standard. This program involves a number of technical challenges relating to instrumentation capable of measuring emissions at these low levels and utilizing this instrumentation to gather data under realistic conditions that will allow assessments of the environmental impact of these advanced vehicle technologies. This paper presents results on the performance and suitability of a Fourier Transform Infrared (FTIR) based on-board measurement system developed principally by Honda R&D for this task. This system has been designed to simultaneously measure vehicle exhaust and ambient roadway pollutant concentrations.Laboratory validation experiments confirm that the FTIR analysis and sampling system is capable of accurately measuring NMHC, CO, and NO at the low concentrations encountered in ambient (roadway) air and vehicle exhaust. Tests with a multi-component hydrocarbon mixture containing components typically found in vehicle exhaust confirmed the FTIR system accurately analyzes complex hydrocarbon mixtures. Chassis dynamometer studies show that the exhaust emission concentrations measured with the on-board FTIR agree well with those obtained with standard emission analyzers. Utilization of the concentration data and exhaust flow rates calculated with data obtained from the engine management system demonstrate feasibility for measurement of mass emission rates. On-board test results are presented for vehicle emissions and ambient/roadway pollution concentrations while operating in the Southern California area. These results demonstrate the potential and value of on-board instrumentation to accurately measure ambient roadway and exhaust emissions.