The nail in the coffin of BMW's beloved N52B30 engine -- known to non-Bimmerphiles as the naturally aspirated 3.0-liter inline six -- gets one more, and possibly fatal hammer-swing with the introduction of the 240 hp, 260 lb-ft N20 2.0-liter turbocharged four-cylinder engine in the X3 crossover. The engine has been well-received by critics in other applications but if you're a fan of the 2012 X3 xDrive28i yet need more fuel economy and higher performance, you're about to get one.

Don't fret, if you absolutely must have a six-cylinder under the hood of your Roundel-festooned ride, the X3 xDrive35i is powered by a turbocharged 3.0-liter inline six. But with the N20 coming very close to the performance of its six-cylinder sibling, with better fuel economy, you might just decide the four fits your needs.

The N20-equipped X3 is thriftier than both its six-cylinder 2012 counterpart, as well as its most direct competitor, the Audi Q5 2.0T, which returns 20/27 mpg city/highway. The six-cylinder 2013 xDrive28i manages 19/25 mpg. Fuel economy figures for the just-announced 2013 Mercedes-Benz GLK 350 4Matic are not yet available, but the 2012 manages a comparatively ravenous 16/21 mpg. The six-cylinder-powered Infiniti EX 35 AWD manages 17/24 mpg.

The 2013 X3 turbo-four may be king of the premium crossover MPG hill for now, but Mercedes-Benz promises unprecedented class fuel economy for the upcoming GLK250 Bluetec diesel, with well above 30 mpg highway a strong possibility.

Source: EPA, BMW