U. S. buyers will first see the S-class as the S550, with a twin-turbo, 4.6-liter, 449-hp V8 under the hood and a seven-speed automatic, in either rear-drive or all-wheel-drive configurations.

美国消费者最早看到的S级轿车会是S550，它配备了最大输出功率为335千瓦的4.6升双涡轮V8发动机，后轮驱动与全时四轮驱动款均配备七速自动变速器。

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Driving the rear wheels via a sophisticated seven-speed automatic transmission, the two power sources make the S400 feel every bit as lively as the conventional S550 version with its 382-horsepower V8 engine.

FORBES: Mercedes-Benz S400 Review: Electrified Flagship