The 333-hp TFSI V-6 is as stealthy and lethal as an assassin’s bullet. It revs so effortlessly and sounds so enticing in the Audi S5, it’s hard to think of this engine excluded from the list.

On a long road trip, we’re convinced 40 mpg (5.8 L/100 km) is within reach in this spacious luxury cruiser with its 8-speed automatic transmission, because diesels, unlike gasoline engines, routinely outperform their stated mileage estimates.

Chrysler’s 3.0L turbodiesel serves up the red meat truck lovers can’t resist. It has a nice grumble, without being overly loud or annoying. Finally, pickup buyers can have the fuel-efficient torque they deserve.

The 500e dashes from stoplights with such confidence that even hard-hearted internal-combustion devotees will find themselves recalibrating their perceptions after a test drive.

The 1.0L EcoBoost is a perfect way to reintroduce a new generation of 3-cyl. car engines to a skeptical American audience. Other automakers gearing up 3 cyls. for the U.S.  should send Ford a thank you note.  

This engine program establishes definitively that old-school cam-in-block configurations relying on pushrods can deliver stunning performance and cost advantages in a powertrain world dominated by newer overhead-cam architectures.

There is a myth that Americans never will accept diesels, yet Volkswagen has found fans in the U.S. for decades. GM is aiming to attract this audience with the Cruze turbodiesel. We think it will succeed.

There’s no denying the punch, power, silkiness and “I’ve got this” attitude of a world-class V-6. For some of them, the tradeoff has been middling fuel economy. Not so for the Honda Accord’s superb 3.5L.

Porsche deserves credit for delivering a compact naturally aspirated engine that feels and sounds so powerful. This is the type of efficient yet diabolically fun powerplant every sports car maker needs to do well as CAFE standards ramp up in the U.S.

VW’s latest 4-cyl. offering sets a new refinement benchmark for small-displacement engines with forced induction. The well-equipped Jetta that delivered this engine to our offices like a holiday gift basket can be had for less than $24,000.