From a sophisticated bread-and-butter 4-cyl. to the world’s most powerful production V-8,

the winners of the 2013 Ward’s 10 Best Engines awards stand as a tribute to internal combustion while auto makers wrestle with fuel-economy standards requiring a growing number of zero-emissions electric vehicles in the future.

Meanwhile, gasoline-fueled engines become more efficient and power-dense every year, and the majority of winners (five) for the second year in a row are 4-cyl. engines.

The transformation within the powertrain community has been rapid as engineering teams now slather attention on downsized engines. As recently as 2005, not a single 4-banger was honored.

This year’s winners:

  • 3.0L TFSI Supercharged DOHC V-6 (Audi S5)
  • 2.0L N20 Turbocharged DOHC I-4 (BMW 328i)
  • 3.0L N55 Turbocharged DOHC I-6 (BMW 135is coupe)
  • 3.6L Pentastar DOHC V-6 (Ram 1500)
  • 2.0L EcoBoost DOHC I-4 (Ford Focus ST/Taurus)
  • 5.8L Supercharged DOHC V-8 (Ford Shelby GT500)
  • 2.0L Turbocharged DOHC I-4 (Cadillac ATS)
  • 2.4L DOHC I-4 (Honda Accord Sport)
  • 3.5L SOHC V-6 (Honda Accord)
  • 2.0L FA DOHC H-4 Boxer (Subaru BRZ)

Although the WardsAuto editorial staff evaluated 11 electric vehicles or hybrids in a field of 40 powertrains during October and November, not a single one made the cut this year.

“When hybrids and EVs have been on the list previously, it was because they were revolutionary and compelling,” WardsAuto World Editor-in-Chief Drew Winter says.

“If next-generation EVs and hybrids raise the bar beyond the current Toyota Prius, Nissan Leaf and Chevrolet Volt, then we’ll be happy to recognize them.”

Now in its 19th year, the Ward’s 10 Best Engines competition pits the latest engines available in the U.S. market against the returning winners from the previous year. To be eligible, an engine must be available in a production vehicle on sale within the first quarter of 2013 and with a base price of less than $55,000.

With so many new engines flooding the marketplace, it has become increasingly difficult for many to stay on the list, which makes the fourth year in a row for Audi’s 3.0L supercharged V-6 all the more remarkable.

Occasionally, WardsAuto editors are eager to boot repeat winners to make room for new blood, but that wasn’t the case with Audi’s blown 333-hp direct-injection V-6 that has driven much of the auto maker’s U.S. success in cars ranging from the sporty S4 to the luxurious A8 and even Porsche and Volkswagen hybrids.

Some WardsAuto editors averaged better than 21 mpg (11.1 L/100 km) in the S5 and raved about the engine’s suave demeanor, whether at idle or wide-open throttle. In the S5, the first-rate engine and transmission go together with the chassis like a Vulcan mind meld.

BMW secures two repeat wins for the 2.0L N20 turbocharged 4-cyl. in the 328i sedan and 3.0L N55 turbocharged inline-6 in the riotous 135is coupe.

The 4-cyl. goes head-to-head with a batch of new 2.0L turbos that are smooth, quiet, powerful and capable of motivating luxury cars as well as 7-passenger SUVs.

But the BMW N20’s calling card is fuel efficiency: Achieving close to 30 mpg (7.8 L/100 km) in the 328i with a European-style stop/start system, the 328i topped its rivals by several miles per gallon. A key enabler is a svelt 8-speed automatic transmission.

A WardsAuto editor describes BMW’s direct-injection 4-cyl., making 120 hp/L with its twin-scroll turbocharger and gratifying low-end torque, as the type of engine many 2.0L turbos hope to be some day. This engine is fast becoming the workhorse in the auto maker’s highest-volume vehicles.

BMW’s other repeat winner, the 3.0L turbocharged inline-6, finds a new application in the small-ish 1-Series that boosts output to 320 hp, up from 300 hp in the original applications in the 3-Series, 5-Series, 6-Series and the X cross/utility vehicles.

The 3-time winner is more than adequate in those bigger, heavier vehicles, so imagine what it can do in a car with a curb weight of 3,373 lb. (1,530 kg) and an additional 17 lb.-ft. (23 Nm) of torque.

The sport-tuned exhaust makes the car sound like a bona fide 1960s muscle car, while achieving nearly 23 mpg (10.2 L/100 km) in our evaluations and always able to make the tachometer needle dance. The direct-injection N55 engine does more work by 2,500 rpm than most engines do at wide-open throttle.

Another stout 2.0L direct-injection turbocharged 4-cyl. that muscles its way back into the winners’ circle with a remarkable 136 hp/L comes from General Motors, in the all-new rear-wheel-drive Cadillac ATS.

This engine replaces a similar 2.0L Ecotec turbo that won a Ward’s 10 Best Engines award last year in the front-wheel-drive Buick Regal GS. But the new version reduces engine friction some 16%; incorporates a more-active continuously variable valve timing system for better breathing; boosts highway fuel economy 4 mpg (1.7 km/L); and positions the ATS to compete head-on with well-established German brands.

GM developed the 2.0L turbo alongside a new naturally aspirated 2.5L 4-cyl., which also was a contender, and the two engines share some componentry, which makes both engines more profitable than those they replace. That’s smart engineering. Installation volumes also will be higher for both engines, which power the ATS and new Chevrolet Malibu.

Ford is one of three auto makers earning two trophies this year, including a repeat winner for the 2.0L EcoBoost direct-injection turbocharged 4-cyl. that has emerged as a dominant piece of Dearborn’s powertrain portfolio.

So flexible and adroit is the 2.0L EcoBoost that it powers most of Ford’s passenger cars and utility vehicles, from the Fusion, fullsize Taurus and 252-hp Focus ST (with exhaust burble piped into the cabin) to the Edge, Escape and 7-passenger Explorer.

WardsAutoeditors drove the newest applications for the 2.0L EcoBoost in the Focus ST hot hatch and approached 28 mpg (8.4 L/100 km) without being gentle, then switched to the 2-ton Taurus family sedan and managed better than 24 mpg (9.8 L/100 km), even loaded down with passengers. It’s tremendously versatile.

Honda returns to the Ward’s 10 Best Engines list with two wins for powerplants in the all-new Accord: the 2.4L 4-cyl. that represents Honda’s first direct-injection engine in North America, as well as a 3.5L port-injection V-6.

The clean-sheet I-4 is stunningly efficient. Over the course of a 537-mile (864-km) test drive, two editors exceeded 33 mpg (7.1 L/100 km) in this generously proportioned sedan that gets up to speed with no problem thanks to 189 hp, ample low-end torque and a wonderful mid-range punch.

A 6-speed manual transmission in the Accord Sport amps up this engine’s fun quotient, but driving enthusiasts also will find the all-new continuously variable transmission, developed internally, to be surprisingly smooth and enjoyable. With excellent transmissions, this isn't just a bread-and-butter 4-cyl. engine. Now it's a piled-high deli sandwich.

The SOHC 60-degree V-6, a Ward’s 10 Best Engines winner in 2005, 2008 and 2009, bows with several significant updates in the Accord and makes a convincing argument that conventional port-injection engines can be powerful and fuel-stingy, while being less expensive to build.

WardsAutoeditors say this engine “positively storms” and “pulls like a freight train at hard throttle,” while feeling much stronger than the 278 hp and 252 lb.-ft. (342 Nm) of torque on the spec sheet.

On the efficiency front, Honda’s VCM cylinder-deactivation system is improved, shutting down three cylinders at a time during light loads. In the past, the system deactivated two or three cylinders at a time. In our real-world evaluations, the Accord V-6 topped 29 mpg (8.1 L/100 km) for several editors, unheard of for most any 6-cyl. engine.

Another outstanding port-injection V-6, the 3.6L Pentastar, comes from Chrysler and earns a Ward’s 10 Best Engines award for the third straight year.

The supremely smooth Pentastar has impressed us in muscle cars, SUVs, CUVs, minivans and luxury sedans, and now it turns in another stellar performance in the fullsize Ram pickup.

Despite its 5,073-lb. (2,301-kg) curb weight, the Pentastar summons a boatload of low-end torque and can tow 6,500 lbs. (2,948 kg), all the while sounding burly and confident and delivering best-in-class fuel economy.

And a new thermal management system raises engine and transmission fluid temperatures more quickly, reducing parasitic losses and improving fuel efficiency 1.7%.

The ’13 Ram, with its sparkling Pentastar mated to an 8-speed automatic transmission, is the first fullsize pickup truck engine to be evaluated and make the Ward’s 10 Best Engines list since 2009, when the 5.7L Hemi V-8 in the Ram pickup won its sixth award in seven years.

Rounding out this year’s list is a 2.0L 4-cyl. boxer engine from Fuji Heavy Industries in the Subaru BRZ coupe that proves forced induction is not essential for engines to achieve today’s high specific outputs.

Churning out an unusually high 100 hp/L, this naturally aspirated “FA” boxer, positioned low in the engine bay to improve the BRZ’s handling characteristics, absolutely succeeds in selling this sporty, lightweight coupe.

Although the BRZ and its Scion FR-S twin were developed with Toyota, Subaru gets credit for the engine. Toyota, however, assisted by providing the unique fueling system that integrates both port- and direct-injection for each combustion chamber.

The 2.0L FA, soon to be joined by a turbocharged version in the Subaru lineup, musters luscious mid-range torque, loves to rev hard and sounds tremendous, while being sedate at idle.

WardsAuto editors hammered the BRZ and still managed nearly 29 mpg (8.1 L/100 km) with the 6-speed manual and nearly 27 mpg (8.7 L/100 km) with the 6-speed automatic. It’s a great daily driver and comes well-equipped for about $25,000.

Diesel-engine aficionados will notice no oil burners on this year’s list. That’s because the only eligible vehicle, the Audi Q7 TDI, with a new 3.0L turbodiesel, was unavailable for evaluation.

But next year’s competition will feature several diesels from auto makers such as General Motors, Ford, Chrysler and Mazda, as well as the Audi Q7.

Ten WardsAuto editors chose the winners by evaluating 40 new or significantly upgraded engines in their routine daily commutes around metro Detroit between October and early December.

Editors scored each engine based on power, technology, observed fuel economy, relative competitiveness and noise, vibration harshness characteristics. There is no instrumented testing.

To be eligible, each engine must be available in a regular-production U.S.-specification model on sale no later than first-quarter 2013, in a vehicle with a base price below $55,000.

Winners from the 2012 competition automatically were eligible and evaluated against the new or improved engines for 2013.

The awards will be presented at a Jan. 16 ceremony in Detroit during the North American International Auto Show.

tmurphy@wardsauto.com