A vehicle emission study was carried out in the Research Triangle Park area of North Carolina to determine the PM (particulate matter) emission rates and emissions profiles of the fleet of in-use vehicles in central California. The NERL (National Exposure Research Laboratory) transportable dynamometer was set-up in the parking lot of Home Depot in Cary, NC. Vehicles from the general area were recruited and tested for their particulate and gaseous emissions. The study was divided into two phase, a winter phase and a summer phase. In the winter phase, 121 gasoline fueled vehicles were tested in Cary and 14 gasoline fueled and three diesel fueled vehicles were tested at NERL, cold cell dynamometer located in the ERC annex at 35 F. In the summer phase, 120 gasoline fueled and five diesel fueled vehicles were tested on the transportable dynamometer in Cary. Samples were collected for all tests for PM 10 (both for mass, and carbon analyses (elemental and organic)), regulated gaseous emissions (carbon monoxide (CO), total hydrocarbons (HC), and oxides of nitrogen (NOx)), and aldehydes. On some vehicle, tests for PM 2.5, organic speciation, and samples for semi- and non-volatile organics were collected. The PM emissions rate were very close to that found in the Denver NFRAQS at 32 mg/mile in the winter and 34 mg/mi in the summer. The Denver study had a PM emission rate of 33.7 mg/mi. In the winter study, the PM 10 and 2.5 were almost identical at 32.8 and 32.5 mg/mi. The eight diesel fueled vehicles had a much higher emission rate at 1781 mg/mi.