Infographic: Automobiles Are Getting Cleaner, But Could Be Better

American cities in the 1960s and 1970s were choked with smog and other pollution from motor vehicles. Clean air legislation and spiking fuel prices led consumers to trade in their land yachts for smaller and more efficient cars. From 1975 to 1985, the average fuel economy for new cars rose from 13.1 miles per gallon to 21.3 mpg. Automotive engineers continued to improve the reliability and efficiency of internal combustion engines, but fuel economy declined until new laws in the mid-2000s spurred a greater emphasis on emissions.
 
The U.S. Environmental Protection Agency recently published its annual Automotive Trends Report, and its data reveals some of the reasons for the way fuel economy and emissions have fluctuated.