When BMW stirred interest by announcing that it will bring four-cylinder engines to the U.S. market again—their last iteration here was the twin-cam four in the 318ti—the big question was: Which cars will get them?
The X1 is the obvious first choice; indeed, journalists drove four-cylinder X128i’s during BMW’s Technology Day in Munich earlier in April. But that car is in such high demand in Europe that its U.S. delivery date keeps being pushed back farther and farther; we don't expect to see them before late 2011, and some pessimists say we won't get the X1 until next year—if then.
So BMW's selection of the Z4 as a nice repository for the N20 was a welcome surprise; it signals a return to the verities of sports-car motoring with a smaller, more-efficient four-cylinder engine.
The move is possible because despite its size, the two-liter N20 ups the ante for efficiency in small engines; combining high-pressure direct injection with BMW’s Valvetronic intake control behind a single twin-scroll turbocharger—hence BMW’s silly “Twin Power” moniker—the N20 produces 240 horsepower and 260 pound-feet of torque That’s more power and torque than the normally aspirated three-liter inline six in the Z430i (a detuned version of the N52 magnesium-sandwich engine, which in some iterations produces around 265 horsepower).
More important, the new engine makes maximum horsepower at 5,000 rpm, 1,500 rpm lower than the six—and peak torque comes on at just 1,250 rpm. With 30% more torque, it also peaks 1,500 rpm earlier. That gives the Z428i—let’s pause to acknowledge the fact that BMW nomenclature is now hopelessly out of alignment with any known descriptive criteria—exactly what you want in a sports car: frog power out of the corners.
The new Z4 is expected to be available this Fall
Source: BMW Car Club of America
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