Spectroscopic techniques in the infrared and ultraviolet spectral regions may efficiently meet increasing measurement challenges in real-time detection of vehicle emissions in urban air quality studies. The results of a study are presented in which a Fourier transform infrared (FT-IR) spectrometer was used to continuously monitor motor vehicle exhaust emissions. The FT-IR identified several exhaust components, including ethylene, acetylene, propylene, isobutylene, the hydrocarbon continuum, carbon monoxide, carbon dioxide, methane, nitric oxide, and nitrous oxide. The emission of each species was shown to vary with vehicle type and the operating speed of the motor. Measurement results from this study support at least two commonly observed characteristics of motor vehicle exhaust. First, ethylene, propylene, and acetylene are common exhaust components. Ethylene was observed to be the most abundant and stable of the non-methane hydrocarbon emissions during idling for the three vehicles considered in this study. Second, the emission of NO as a function of time remains high and fairly constant at high speeds, while the concentrations of CO, HC, and the non-methane hydrocarbons decrease sharply. The results of this study strongly suggest that the FT-IR can serve as a continuous, real-time monitor for measuring motor vehicle emissions. Because it can simultaneously detect multiple pollutants and can operate in an automated fashion, the FT-IR represents a cost-effective means of determining the effect of vehicle emissions on air quality.