Prompted by high oil prices and tight new fuel-economy regulations, automakers are replacing six-cylinder engines with more-economical but less-powerful four-cylinders throughout their lineups. BMW resisted this trend until it developed a four-cylinder that actually outperforms its six. A pricey twin-scroll turbocharger and high-pressure electronic fuel injectors increase compression and wring more power from each drop of fuel. As a result, the TwinPower four-cylinder produces 240 horsepower and 260 pound-feet of torque—40 pound-feet more than the 3.0-liter six it replaces—while consuming up to 23 percent less fuel. The engine first goes into the 2012 528i sedan and Z4 sDrive 28i convertible.