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摘要

When two turbos were no longer enough, BMW applied three to make its straight-six diesel the most powerful in its class and deliver more torque than the M5's gasoline V8. Sequential boosting is a mature technology now but, when BMW first used it in 2004 to make its straight-six diesel more potent, it marked a step-change in engine development. Connecting one small and one large turbo in series meant that low-end torque and top-end power were both far higher than what the single-turbo 3-litre unit could produce.