This report presents EPA technical staff current assessment of the costs and effectiveness from a broad range of technologies which can be applied to cars and light-duty trucks. The report is divided into four major sections. In Section 1, we discuss the methodology used to develop cost and effectiveness estimates, including what data sources we relied upon. In Section 2, we present our estimates of the carbon dioxide (CO2) reduction potential of nearly 40 individual technologies covering five broad categories: engines, transmissions, hybrids, accessories, and others (e.g., aerodynamic improvements). These estimates are for individual technologies compared to a baseline vehicle, and the estimated effectiveness cannot simply be added up when considering a combination of technologies. This issue is addressed in Section 3 of the report, which discusses the synergistic effects of combining multiple technologies and provides an estimate of the magnitude of this impact on CO2 reduction effectiveness. Finally, Section 4 provides an estimate of the direct costs associated with each of the technologies, as well as a discussion of estimating indirect costs and the potential for future cost reductions.