Second by second emission data for 80 FTP (Federal Test Procedures) UDDS Runs on 13 vehicles are included. Product gives the results of analyses using real-time dynamometer test emissions data from 13 passenger cars to examine variations in emissions during different speeds or modes of travel. The resulting data provided a way to separately identify idle, cruise, acceleration, and deceleration emissions for examining how emissions differ by vehicle speed during the cruise mode. To select a set of vehicles for the study, the hydrocarbon (HC)/time relationship was established for several vehicles operating on summer-grade fuel. Federal Test Procedure results were then produced and examined to identify normal emitters (clean vehicles). After these vehicles were selected, their second-by-second emission characteristics were analyzed. The FTP runs for cold start, hot start, and hot stabilized emissions (Bags 1, 2, and 3 of the FTP) were performed for each of the four driving cycles-acceleration, deceleration, idling, and cruise-and the fraction of overall emissions contributed by each mode was computed for the warmed-up portion of the driving cycle. A protocol was then developed for review of the FTP real-time data. Study results showed significant emissions differences relating to the travel mode.