BMW brings a four-cylinder engine back to the United States, and has the decency to make it a turbo. The last four-potter was a 1.9-liter naturally aspirated thing plonked into in the ’99 Z3. In the meantime, BMW has been making rather nice engines with two fewer cylinders than its trademark straight sixes, while mastering the arts of variable valve timing and direct fuel injection. With a twin-scroll turbo attached, this 2.0-liter unit can develop a healthy 240 hp and 260 lb-ft of torque. It isn’t clear which of these numbers relates to the one in the ’12 Z4 sDrive28i, but that’s the car into which the new engine will be offered to American buyers. BMW reckons the turbo four-pot will improve fuel consumption by 20 percent over the current non-turbo Z4 sDrive30i, rated at 18 mpg in the city and 28 mpg on the highway. This new model comes out in the fall; no price yet, but the current 3.0-liter version starts at $46,500. Expect other BMW models to carry this engine option as they come onstream.