Fuel prices have become a critical motivator in convincing American buyers to choose smaller engines, especially with improvements in the latest powertrain technology. Four-cylinder engines now account for 43% of the U.S. automotive market, up from 26% in 2005, while six-cylinders dropped from 43% to 37%. Interest in V-8 engines has dipped from 29% to just 18% over the past six years with predictions of further declines. Automakers have been under pressure to develop fuel-saving technologies to meet the 2016 Corporate Average Fuel Economy standard of 37.5 mpg.