While new cars and light trucks emit about 90 percent fewer pollutants than three decades ago, total vehicle miles driven have more than doubled since 1970 and are expected to increase another 25 percent by 2010. The emission reductions from individual vehicles have not adequately kept pace with the increase in miles driven and the market trend toward more polluting light trucks. Pollution breaks were originally granted to light trucks because they were used primarily for hauling heavy cargo, they comprised a small share of the new vehicle market, and the state of engine and catalyst technologies were not advanced enough to achieve car-equivalent emissions. However, the situation has changed dramatically on all of these points in recent years. In fact, a study by the former American Automobile Manufacturers Association found that only 15 percent of all sport-utility vehicles are ever used for towing.
Light trucks are the new passenger cars of choice, representing half of new vehicle sales.
This trend toward light trucks has resulted in significant erosion in the benefits of government efforts to reduce air pollution from motor vehicles. This is equivalent to the pollution from 40 million cars, five times the number of cars sold last year. New emission standards must account for the fact that some light trucks are used to tow heavy loads. Fortunately, modern technology enables light trucks to meet car-equivalent emission standards while retaining their hauling capabilities, due to dramatic improvements in the technology to control air pollution from engines and the durability and efficiency of catalytic converters. This is one of the cheapest air pollution mitigation investments that can be made.