This report summarizes key trends in carbon dioxide (CO2) emissions, fuel economy, and CO2- and fuel economy-related technology for gasoline- and diesel-fueled personal vehicles sold in the United States, from model years (MY) 1975 through 2012. Personal vehicles are those vehicles that EPA classifies as cars, light-duty trucks, or medium-duty passenger vehicles. The data in this report cover the MY 1975-2012 timeframe, supersede the data in previous reports in this series, and, for many important reasons, should not be compared with data from previous years editions of this report. Most CO2 emissions and fuel economy values in this report have been adjusted to reflect 'real world' consumer performance and therefore are not comparable to CO2 emissions and fuel economy standards.