For the 12th year in a row, the US-based Ward's AutoWorld magazine has issued a list of 'best engines'.

Engines and the vehicles they were evaluated in are:

Audi AG: 2L FSI turbocharged DOHC I4 (Audi A3)
Audi AG: 4.2L DOHC V8 (Audi S4)
BMW AG: 3L DOHC I6 (330i)
DaimlerChrysler AG: 5.7L Hemi Magnum OHV V8 (Charger R/T)
Ford Motor Co: 4.6L SOHC V-8 (Mustang GT)
General Motors: 2L supercharged DOHC I4 (Chevrolet Cobalt SS)
General Motors: 2.8L turbocharged DOHC V6 (Saab 9-3 Aero)
Mazda: 2.3L DISI turbocharged DOHC I4 (Mazdaspeed 6)
Nissan Motor: 3.5L DOHC V6 (Infiniti G35 6MT)
Toyota: 3.5L DOHC V6 (Lexus IS 350)

Two important engineering developments are fitted to several engines on this year's list: direct injection gasoline (DIG) technology and forced induction.

Ward's AutoWorld noted that DIG technology is emerging as one of the most promising new developments in powertrains.

"Injecting fuel directly into each of the engine's cylinders produces outstanding performance and emissions improvements for new-generation diesels [most of which, ironically, are denied to US buyers because of sub-standard fuel and unfavourable emissions laws]. Engineers now are using the technology for gasoline engines to generate improved low- and mid-range torque and in many cases to conserve fuel," the magazine said.

DIG systems are on three of this year's best engines winners and the technology is widespread throughout Audi 's engine lineup and becoming common across the European Volkswagen range as well.

The so-called FSI system (an acronym for "Fuel Straight Injection"), combined with a variable-geometry turbocharger, helps Audi's diminutive [by US standards] two-litre powerhouse produce 100 horsepower per litre - an industry benchmark for performance.

Mazda follows a similar formula for its winning 2.3L DISI DOHC I4 powering the new Mazdaspeed 6 sport sedan, which will be known as the 6 MPS when launched in Europe in January. This new engine combines DIG technology and turbocharging to generate 274 horsepower - a remarkable 119 horsepower per litre, noted the magazine, adding: "The engine produces a V8-like 280 lb.-ft. of torque and a respectable 19 mpg in the city and 25 mpg on the highway".

A variation of this engine tuned for more low-speed torque will be in Mazda's new CX-7 crossover/SUV due for US launch early in 2006.

Toyota also uses DIG for its Lexus 3.5L DOHC V6.  Generating a new benchmark of 306 horsepower from its normally aspirated 3.5 litres, the new engine adds a novel approach of combining DIG with a conventional port fuel-injection system to deliver its high horsepower combined with an impressive EPA fuel economy rating of 21 mpg in the city and 28 mpg on the highway along with high levels of refinement.

"DIG technology is the most important development the powertrain sector has seen in this decade," said Bill Visnic, Ward's senior technical editor. "Particularly combined with turbocharging, direct injection for gasoline engines is permitting engineers to design smaller, more power-dense engines that provide the ever-higher performance levels that customers have come to expect."

General Motors won two awards for new engines this year. The magazine said "GM makes serious inroads into the affordable performance market with its thrilling 2L supercharged DOHC I4 used in the Cobalt SS performance coupe.  Thanks to supercharging and intelligent design, GM engineers squeeze more than 100 hp per liter from their 4-cyl. dynamo, while achieving an impressive 23/29 EPA city/highway fuel economy rating".

The 2.8L turbocharged DOHC V6, currently used exclusively by GM's Saab brand for variants of its 9-3 sport sedan and wagon, also won plaudits. This variant of GM's sophisticated "global" V6 engine architecture, "tuned in the Saab application for an outstanding mix of performance and refinement, while underscoring Saab's heritage for turbocharged engines".

"A sophisticated mid-displacement V6 and turbocharging are a remarkably effective combination," said Visnic. "GM and Saab have created an impressive performance car engine with high specific output and the thrill of turbocharging."

BMW, long acclaimed worldwide as a maker of superb engines, was noted for its latest 3L DOHC I6. "BMW engineers have dramatically improved the company's hallowed inline 6-cylinder design to produce more power while simultaneously delivering markedly improved fuel economy and reduced emissions. True to BMW's heritage for sophisticated engineering, the new BMW 3L inline 6-cyl. employs an innovative new construction technique of magnesium and aluminium for the engine block that enabled significant weight reduction," gushed Ward's AutoWorld.

Over two months, six editors evaluated engines from 31 different cars, trucks and SUVs sold in the US.

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