A commercial PEMS, the SemtechD, was evaluated for its suitability to measure transient emissions from light-duty, oxidation catalyst equipped, diesel passenger cars. The PEMS was evaluated for its analytical capabilities in a state-of-the-art chassis dynamometer test facility. The system, manufactured by Sensors, Inc of Saline, MI, proved to be both accurate and precise. The SemtechD proved capable of measuring THC concentrations (FID-based measurement) as low as 2 ppmC with measurements on average within 4.5% of those reported by modal test cell instrumentation. Similarly, both CO and NOx measurements fell within 9% and 3% of the values reported (respectively) by modal test cell analyzers. Finally, modal CO2 agreed within 2.6% of the two measurement systems across eleven vehicle tests and with more than 6000 data points compared.