The Taming of the Turbo

© Volvo Cars of North America© Volvo Cars of North America
Volvo S90 T6 AWD
Starting MSRP: $54,100
Here’s what happens when an automaker can’t decide how to pressurize an engine. Volvo’s 2.0-liter four cylinder is both supercharged and turbocharged. Both methods compress air toward more efficiency — the major difference is how each compressor gets powered. A supercharger is driven by a belt and pulley, while a turbo relies on exhaust gasses from the engine to spin its turbine wheel, which in turn spins the compressor wheel on the end of a common shaft. The result of Volvo’s twin-charging is impressive: The S90 T6 brings 316 horsepower to the party — a specific output of 158 horsepower per liter. All that while delivering impressive fuel efficiency of 22 mpg city / 31-mpg highway / 25 mpg combined.

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