This study measured CH3Br emissions directly from vehicular exhaust while operating under standardized dynamometer conditions, and generated response curves to see if the bromine content of the fuel could be correlated to and used as a predictor for tailpipe emissions. Four lead and bromine fuel concentrations were run in two non-catalyst automobiles using the standard Federal Test Procedure (FTP) driving cycle and exhaust samples were analyzed for CH3Br using Gas Chromatography-Electron Capture Detection (GC-ECD). Total FTP exhaust emissions of CH3Br produced a range of average values from below detection to 26 mg (kg fuel burned)-1. Total FTP Emission Rates were plotted and response curves demonstrated that fuel bromine content was indeed predictive of CH3Br emission rates. Overall average CH3Br mass emission factor was 2.4% (2.1--2.7%) which was lower than previous work. Emission results of this study were found to be about 10-fold lower than indirect methods. ¿ 2000 American Geophysical Union