· 83-kW Electric Motor (Fiat 500e)

It's the end of the year, which in the auto industry means various 'of the year' lists are appearing to sum up the most significant new cars and trucks of the past 12 months. In addition, one of the most watched parts of this automotive award season is the annual Ward's Auto 10 Best Engines list.

The jurors at Ward's evaluated 37 new or improved powertrains and—showing automakers' current emphasis on fuel economy—that group included 15 turbocharged four-cylinder engines, four electric powertrains, and the first-ever hydrogen fuel-cell powertrain to be eligible for the award. They made up what the jurors called the most diverse field ever.

Here are Ward's 10 best engines for 2015:

127-kilowatt electric motor (BMW i3)
6.2-liter OHV V-8 (Chevrolet Corvette Stingray)
6.2-liter Supercharged OHV V-8 (Dodge Challenger SRT Hellcat)
1.0-liter Turbocharged DOHC 3-cylinder (Ford Fiesta)
100-kW Fuel Cell (Hyundai Tucson Fuel Cell Vehicle)
1.5-liter Turbocharged DOHC 3-cylinder (MINI Cooper)
3.0-liter Turbodiesel DOHC V-6 (Ram 1500 EcoDiesel)
2.0-liter Turbocharged H-4 (Subaru WRX)
1.8-liter Turbocharged DOHC I-4 (Volkswagen Golf)
2.0-liter Turbocharged DOHC I-4 (Volvo S60)

The supercharged 6.2-liter Hellcat V-8 from Dodge has generated plenty of buzz everywhere else, and with 707 horsepower it certainly has the muscle to be considered a great engine. It's joined by another 6.2-liter V-8, the naturally-aspirated small block from the Chevrolet Corvette Stingray, which was eligible again because it made the list last year. The 2015 Subaru WRX's boxer four also made the cut.

The two V-8s were outliers. They each have just over twice the displacement of the next biggest engine-—the 3.0-liter EcoDiesel V-6 from Ram—and the Chevy small block was the only naturally-aspirated engine to make the list this year.

Stretching the definition of "engine" were the BMW i3's electric motor—the second electric powertrain to make the list—and Hyundai's fuel-cell powertrain.