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 2011. Personal vehicles are those vehicles that EPA classifies as cars, light-duty trucks (sport utility vehicles, minivans, vans, and pickup trucks with gross vehicle weight ratings up to 8500 pounds), or, beginning in MY 2011, medium-duty passenger vehicles (sport utility vehicles or passenger vans with gross vehicle weight ratings between 8500 and 10,000 pounds). The data in this report cover the MY 1975-2011 timeframe, supersede the data in previous reports in this series, and should not be compared with data from previous years editions of this report due to changes discussed below. Except when noted, 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.