Green is the new big. And for BMW, it wants to dispel the notion that more cylinders always equate to more output, and more output must equate to less fuel efficiency. To deliver that message in real terms, it has introduced a new turbocharged 4-cylinder engine into the 2012 Z4 roadster lineup in the US .
Code name the N20, the new 2.0-liter single twin-scroll turbocharged 4-cylinder engine replaces the normally aspirated 6-cylinder in the . Even though rated at 240 bhp (6 percent less compared to the six's power), the forced-induction 4-banger comes out on top with 260 lb.-ft. of torque (18 percent more than the six's). With direct injection and BMW's Valvetronic on the intake side, the company has attached the moniker TwinPower to this type of engine configuration. Weighing 22 lb. lighter, and with those two cylinders lopped off, the N20 helps make the Z4 more balanced by hanging less weight up front and closer to the car's center of gravity. Equipped with a 6-speed manual transmission, the turbo 4-cylinder Z4 can race to 60 mph from a dead stop in 5.5 seconds, 0.1 sec. faster than the normally-aspirated 6-cylinder. Of note, there is also a no-cost option of ordering BMW's slick 8-speed automatic with the N20 powerplant.
On our recent drive from Los Angeles up the beautiful California central coast to Monterey , the N20 Z4 was impressive. With many turbo engines, the exhaust note tends to be muffled. But this was not the case for this turbo-4. It had a nice low-end growl that was surprising. And the bump in torque also matched this more aggressive engine sound. Passing 5000 rpm, you can begin to feel and hear the engine's roughness, due to the 4-cylinder running out of steam and needing to work harder to keep up. (more)
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