Trends in energy use and energy intensity in transportation are analyzed by growth in transportation activity, changes in energy intensity, and changes in modal structure. Trends in the fuel economy of light-duty vehicles are also analyzed. Reductions in the energy intensity of transport have held back the growth of energy use but with widely varied success across modes. Analysis of trends in the fuel economy of new passenger cars and light trucks from 1975 to 1993 shows that changes in the vehicle sales mix have had a relatively minor impact and that decreased vehicle weight has boosted fuel economy by 0.85 km/L (2 mpg). Increased performance has erased almost all of that gain, though, so the increase for new vehicles is due almost entirely to improved fuel economy technology.