Environmental impact of vehicle exhaust
Automobiles generally use petrochemical fuels such as gasoline and diesel as power sources. They emit carbon dioxide and other exhaust gases during vehicle operations, which is one of the causes of air pollution, global warming and acid rain. The US Environmental Protection Agency counts that every carat of gasoline consumed will produce 8,887 grams of carbon dioxide, which will produce 10,180 grams of carbon dioxide per gallon of diesel. Therefore, improving fuel efficiency to reduce exhaust emissions has become an important issue. Many countries use fiscal policies such as road taxes or energy taxes to reduce vehicle purchases. In addition, in order to solve these problems, the development of electric vehicles and hybrid vehicles is also a hot development direction, and has attracted many automobile manufacturers to invest in research and development. To this end, many developed countries have promoted various incentives by the government to try to solve the environmental problems caused by the heavy use of automobiles. Fuel taxes can effectively reward vehicles that are more efficient or less polluting (such as electric vehicles, hybrid vehicles, or vehicles with alternative fuels). High fuel taxes can effectively make consumers consider buying smaller, lighter, more fuel-efficient cars, or even not driving. On average, 75% of current cars are recyclable, and recycled steel can reduce energy consumption and pollution. The US Congress regularly discusses fuel efficiency set by the federal government. The bus standard was set in 1985 with a fuel efficiency of 27.5 miles per US gallon (8.6 liters per 100 kilometers; 33.0 miles per inch of gallon), light trucks. The standard was revised in 2007 with a fuel efficiency of 22.2 miles per US gallon (10.6 liters per 100 kilometers; 26.7 miles per inch of gallon).