General Motors provided an overview of how its all-new 2014 Chevrolet Cruze Clean Turbo Diesel’s 2.0L engine uses what the automaker calls a “variable-swirl intake system” to improve performance and reduce emissions.

The company’s Mike Siegrist, 2.0L turbo diesel assistant chief engineer, explained that the “variable swirl” increases the mixture motion of air and fuel in low-speed, low-load driving, for example when commuting. In the variable-swirl intake manifold, each cylinder has two separate intake ports and one of them is controlled by a valve. During the variable-swirl process, each throttle valve varies how much it opens in order to create the mixture-motion of air and fuel in each cylinder. GM said its powertrain engineers focused on calibrating the actuator so it precisely opens and closes the engine’s valves in order to optimize performance.

As noted in Automotive Fleet’s earlier coverage, the Cruze Clean Turbo Diesel can achieve 46 mpg highway, but the 2.0L diesel engine is the cleanest ever produced by GM, according to the automaker. GM said the vehicle will meet U.S. Environmental Protection Agency’s (EPA) Tier 2 Bin 5 emissions standards.