During emissions testing, the cars' pollution controls systems were turned on, curbing toxic emissions at the cost of engine performance.

在排放检测中，车辆的污染控制系统会被打开，遏制发动机性能，削减有毒物质的排放。

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The testing required to demonstrate that a novel engine can meet stringent emissions standards and durability requirements is expensive and time consuming.

WSJ: How to Make Better Car Engines