This report summarizes key fuel economy and technology usage trends related to model year 1975 through 2000 light vehicles sold in the United States. Light vehicles include those vehicles that EPA and the U.S. Department of Transportation (DOT) classify as cars or light-duty trucks (sport utility vehicles, vans, and pickup trucks with less than 8,500 pounds gross vehicle weight ratings). The report finds that since 1988 average new light vehicle fuel economy has declined 1.9 miles per gallon (mpg),i.e., more than seven percent, primarily because light truck market share has increased and because fuel economy has been traded off for increased vehicle weight and performance. The fuel economy values in this report are laboratory data and are significantly higher than the real world estimates used on new vehicle labels and in the Fuel Economy Guide. The fuel economy values in this report are similar to those used by the DOT for compliance with fuel economy standards, but because the values in this report exclude correction factors for alternative fuel capability and test procedure adjustments, they are always lower than those reported by DOT.