The United States Environmental Protection Agency (EPA) is in the process of creating a new mobile source emissions modeling system entitled the Multi-Scale Motor Vehicle and Equipment Emission System (MOVES). This new model will generate emissions factors in units of grams per second. This is a marked difference from previous models, such as MOBILE6, which were based on factors in grams per mile. Much of the new factor development will be based on the vehicle testing information contained within EPA's Mobile Source Observation Database (MSOD). The goal of this project is to augment the data currently in the MSOD with data collected by other entities such as research groups and industry organizations. Towards this end, ERG staff have contacted numerous vehicle-testing organizations and investigated the availability of vehicle testing data. This investigation focused on tests that recorded second by second emissions results with emphasis placed on greenhouse gas exhaust emissions, i.e CO(sub 2), CH(sub 4), and N(sub 2)O. Each of the different data sources were questioned by EPA or ERG staff to determine what type of vehicle test data they have that could be included in the EPA MSOD and made available for public access. The available data can be generally grouped as stemming from either an inspection and maintenance (I/M) program, or a special study. This report presents a review of the different datasets that are of interest and are being considered for inclusion into the MSOD. In some instances only a sample of the data was available for review at the time that this report was written and the statistics presented should be taken as only an example of the type of information that is available. Also included in this report is a brief discussion of other datasets that have been determined to be available outside of the time frame of this project. These datasets will be discussed briefly and highlighted for possible examination in the future.