An engine is arguably the most important component of any car; without one, a car is simply an expensive sculpture. This year we’ve sampled dozens of engines in scores of new cars, ranging from innovative four-cylinders to high-performance V-8s. Whether by innovative efficiency or pure accelerative might, some of those engines impressed us more than others. Here, in order of displacement, are our favorite engines of 2011. 1.4-liter MultiAir inline-four -- 2012 Fiat 500; 101 hp, 98 lb-ft This tiny 1.4-liter engine is found under the hood of an equally small car -- the Fiat 500. Fitted with the company’s MultiAir intake valve system, the four-cylinder engine extracts remarkable power and torque for such a small, non-turbocharged engine. The engine also is thrifty, returning up to 30/38 mpg (city/highway) in the Fiat 500 with a five-speed manual transmission. The best is yet to come, though, as Fiat will soon launch the U.S.-spec 500 Abarth with a turbocharged version of this engine. The hot mill will produce 160 hp and 170 lb-ft, although crash regulations prevent it from being mated with anything greater than a five-speed gearbox. Turbocharged 2.0-liter N2O inline-four -- 2012 BMW Z4 sDrive28i, 328i, 528i; 240 hp, 260 lb-ft In a move that may have shocked brand purists, BMW replaced the base inline-six engine in the 328i and 528i with a turbocharged four-cylinder. Codenamed the N20, the new 2.0-liter turbo-four has a wider torque band than the 3.0-liter six it replaced, and also is significantly more fuel efficient. A BMW Z4 sDrive28i with the new engine can hit 60 mph in a claimed 5.5 seconds, a tenth of a second quicker than the prior 3.0-liter model. In the 5 Series and new 3 Series sedans, the N20 likewise provides ample torque and acceleration, while consuming less fuel than its predecessor. The 2012 528i receives EPA ratings of 23/34 mpg -- up from 22/32 mpg for the 2011 528i. The trio of BMWs proves that turbocharged four-cylinder engines are still suitable for sports cars and luxury machines. 2.0-liter SkyActiv-G inline-four -- 2012 Mazda 3, 2013 CX-5; 155 hp, 148 lb-ft (Mazda 3) The SkyActiv-G engine is the first U.S.-market fruit of Mazda’s aggressive new strategy to cut emissions, broadly called SkyActiv. Special pistons, fuel injectors, a 12:1 compression ratio, and other innovations help Mazda’s 2.0-liter inline-four deliver a solid mix of fuel economy and performance. In the 2012 Mazda 3 sedan, the engine returns 40 mpg on the highway with an automatic transmission, yet still feels peppy in all driving situations. SkyActiv-G will also appear in the 2013 CX-5 crossover, which Mazda claims will return up to 26/33 mpg with front-wheel drive and a manual transmission. In the future, SkyActiv engines and transmissions will roll out across Mazda’s lineup, proving that it’s possible for cars to be both fuel efficient and fun to drive. Turbocharged 2.5-liter TFSI inline-five -- 2012 Audi TT RS; 360 hp, 343 lb-ft The key ingredient that transforms the Audi TT from a regular sports coupe into an outstanding performance machine is a turbocharged five-cylinder engine. The 2.5-liter mill, packing 144 hp per liter, showcases the Volkswagen/Audi group’s expertise with high-performance turbocharged engines. Power delivery is strong and smooth across the rev range, with 343 lb-ft of peak torque available from 1650-5400 rpm. Audi says the TT RS will crack the 60-mph mark in 4.1 seconds, a feat accompanied by a burbling hum from the five-cylinder mill. Upgraded brakes and suspension also help make the TT RS great on the race track, but it’s the new engine that solidifies the TT’s components into one great sports car. 3.6-liter Pentastar V-6 -- Chrysler, Dodge, Jeep, Ram vehicles; 292 hp, 260 lb-ft (Chrysler 300) The Chrysler Group’s new Pentastar V-6 can be found in nearly all of the company’s vehicles, from the Chrysler 300 sedan to the Jeep Wrangler to the Ram Commercial Van. The 3.6-liter V-6 is more powerful, more fuel efficient, and smoother than the old Chrysler V-6 engines it replaces. Every vehicle blessed with the Pentastar has been radically improved by the new engine, whether because it is now quicker or because it is significantly more economical. Chrysler has started offering an eight-speed automatic for the engine in certain applications, allowing the luxurious Chrysler 300 to return up to 31 mpg highway. Compared to the V-6 engines it replaces, the Pentastar is perhaps the biggest improvement on this list. 4.5-liter V-8 -- Ferrari 458 Italia/Spider; 562 hp, 398 lb-ft Modena’s craftsmen have built plenty of lust-worthy engines over the years, and the 4.5-liter V-8 in the Ferrari 458 Italia and 458 Spider is no exception. With a screaming engine note and a sky-high 9000-rpm redline, the V-8 is an engine unlike any other in a production car. So addictive is the scream from the engine that Ferrari specifically tweaked the exhaust in the 458 Spider for maximum aural pleasure. The 0-to-62-mph dash takes just 3.4 seconds, and the car’s top speed is nearly 200 mph. We have no choice but to love any engine capable of such breathtaking performance and heart-wrenching sound. 5.0-liter Ti-VCT V-8 -- 2012 Ford Mustang Boss 302; 444 hp, 380 lb-ft The numbers for Ford’s burly Mustang Boss 302 tell the whole story: 444 hp, 380 lb-ft, and a 7500-rpm redline -- with regular 87-octane gasoline. The all-aluminum 5.0-liter V-8 engine in the Boss is a significantly reworked from the version found in the regular Mustang GT, with new intake runners, revised programming, and other modifications to extra additional power. The result is a street-legal muscle car that sounds fantastic and offers heroic levels of performance, thanks to an aggressive yet tractable V-8 engine. Owners can even remove two small baffles on the Boss’s side exhaust pipes to make the car even louder, although that’s recommended only for track use. We confidently praised the Boss 302 as the best muscle car ever, a commendation due in no small part to the car’s outstanding powerplant.