According to Wards, only new or significantly reengineered engines or propulsion systems that are available for sale in the US and are installed in cars having a base price of less than $61,000 are eligible for the top 10. In addition, the winners from the previous year are also eligible to defend their crowns. But all VW Group products were banned this year from the list, as a result of the company's ongoing emissions scandal.
A total of 31 candidates were evaluated by the publication's editors in real-life, on-road driving conditions in October and November. Wards scored each engine based on horsepower, torque, comparative specs, noise attenuation, fuel economy, and application of new technology.
The Ford Shelby Mustang GT350 is one of the hottest pony cars to reach production in recent memory. At its heart is a snarling 5.2-liter, 526-horsepower V8 engine known as the "Voodoo."
Wards editors found the powerful V8 to be equally competitive at mundane street driving or at pushing the boundaries of its performance. As a result, the publication calls the Voodoo "the pinnacle of internal-combustion engineering."
The 3.6-liter LGX V6 engine is the first of two power plants from General Motors to make the list this year. According to Wards, the 335-horsepower, fuel-efficient V6 proves that the six-banger is no longer just a consolation prize for missing out on the V8.
The direct-injected V6 can be found in Cadillac's sleek ATS and ...
... the new Camaro.
The second entry from GM is the 1.5-liter inline 4-cylinder and hybrid-electric system from the Chevrolet Volt.
According to GM, the Volt is capable of 53 miles of all-electric range and a total gas/electric range of 420 miles. Wards editors achieved an incredible 229 MPGe of fuel economy while evaluating the car.
Wards was also highly impressed by the hybrid system on the Hyundai Sonata PHEV. The hybrid sedan returned 41 to 80 mpg of fuel economy during testing.
Wards found the Sonata Hybrid's 2.0-liter, 154-horsepower, 4-cylinder engine "enormously fulfilling and smooth to drive."
You can't talk about hybrids without mentioning the Toyota Prius. This year, the Prius returns to the winner's circle for a fourth time.
Wards found the Prius' new 1.5-liter, 95-horsepower, inline 4-cylinder, and 71-horsepower electric motor to be quieter and silkier than the outgoing model. According to the publication, the
new Prius returned 61 mpg of real-world fuel economy.
The Ram 1500's 3.0-liter, EcoDiesel V6 engine is the first of two holdovers from last year's winners. In fact, this is the EcoDiesel's third win in a row.
With 420 pound-feet of torque on tap and 25 mpg, Wards calls the Italian-built engine the "gold standard for refinement and fuel economy" for the segment.
The other returning winner from 2015 is Subaru's potent 2.0-liter, 268-horsepower, turbocharged boxer 4-cylinder.
The powerful engine makes the WRX one of the most sought-after performance cars on the market today.
Last year, Volvo's 2.0-liter, 240-horsepower turbocharged Drive-E engine took home one of Wards' trophies. This year, Volvo's Drive-E is back with a turbocharger and a supercharger.
The 316-horsepower engine powers Business Insider's 2015 Car of the Year: the Volvo XC90 T6.
Nissan's VQ Series V6 engine returns to Wards' top-10 list. With the latest variant from the new Maxima, the venerable engine makes its 15th appearance on the list since 1995.
With 61% of its parts redesigned, the VQ makes its first appearance since 2008. Editors were impressed with Nissan's strong mid-range torque and lively yet refined power delivery.
Finally, there's BMW's new B58 3.0-liter, inline 6-cylinder. This is BMW's 32nd trophy in the competition in 22 years.
Although it produces 320 horsepower, there are lots of motors that make more. But Wards lauded the engine, saying, "BMW proves once again an engine need not make outrageous horsepower or torque numbers to be enormously rewarding and thrilling to drive."