BMW's B58 engine made the list last year, and it does again thanks to a bump in power.
You'll find this one tucked under the hood of the BMW M240i (formerly known as the M235i).
Chevrolet's extended-range electric powertrain is yet another entrant that appeared on previous lists.
This one lives inside the second-generation Chevrolet Volt, which is a much sleeker car than its forebear.
A newcomer to the WardsAuto list, this is Chrysler's first hybrid minivan powertrain.
The Chrysler Pacifica Hybrid also happens to be the first hybrid minivan ever built, with an EPA-estimated 84 MPGe.
Turbochargers aren't just for thrift, they're also for fun, as evidenced in this new entry to the WardsAuto list.
The Focus RS that houses this four-banger is a real stunner, too.
The Accord Hybrid's powertrain is the only traditional hybrid to make the list this year.
Several reviewers have recorded real-world fuel economy estimates north of 50 mpg with this bad boy.
Hyundai's Kappa four-cylinder engine delivers big fuel economy figures for relatively little money.
Living inside the Elantra Eco, it only costs about $22,000 to get up to 40 mpg.
Another newcomer this year is Infiniti's 3.0-liter VR-series V6.
When living inside the Q50 or Q60, the engine can put out either 300 horsepower or 400, depending on the buyer's preferences.
This engine marks the first time Mazda mixed its Skyactiv engine tech and a turbocharger.
The result, as seen in the CX-9 crossover, is V6-like torque with four-banger fuel economy.
WardsAuto added this Mercedes four-pot to the list for its peak torque, which starts at just 1,300 RPM, yet it returns nearly 30 mpg.
You can find this engine in several variations of Mercedes-Benz product, like the C300, C300 Coupe, C300 Cabriolet and E300.
What happens when you mix Volvo's excellent twin-charged motor with a bigger turbo and beefier supporting parts? You end up on this list, that's what happens.
This supercharged and turbocharged masterpiece lives inside Volvo's hopped-up V60 Polestar.