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Although the 2009 Audi TT has improved greatly on previous models in terms of general fun-factory and handling, enthusiasts still don't place it in the same league as the M Coupes, Boxter/Caymans and S2000s of the world. The S line model, which debuted in 2008, served up a big helping of improvements, but Audi fans still wanted more.

Audi is once again producing a five-cylinder engine – and a very special one at that. Arriving at dealerships this summer, the TT RS has a turbocharged 2.5-liter engine with direct gasoline injection; it produces 250 kW (340 bhp) and 450 Nm (331.90 lb.-ft.) of torque. The blazing five-cylinder engine enables the TT RS to perform extraordinary feats. In conjunction with quattro permanent all-wheel drive and a high-performance chassis, the engine makes the compact Audi TT RS a top-notch sports car – available as a coupé or roadster.

Sporty five-cylinder gasoline engines have a long legacy at Audi. The most famous is arguably the turbocharged 2.1-liter engine in the Audi quattro. The first version, which was launched in 1980, offered an impressive 147 kW (200 bhp). And the Sport quattro from 1984, directly inspired by motorsport, delivered a whopping 225 kW (306 bhp). For 25 years, turbochargers and quattro have been a dynamic formula for success.

Audi has resumed using this recipe. Designed from scratch, the five-cylinder engine combines a turbocharger with FSI direct gasoline injection to elevate the TT RS to a high-performance sports car. The TFSI delivers 250 kW (340 bhp) from a displacement of 2,480 cc (151.34 cu in): a specific output of 100.8 kW (137.1 bhp) per liter.

The power-to-weight ratio is also outstanding. In the case of the Coupé, which weighs in at a mere 1,450 kilograms (3,196.70 pounds), the power-to-weight ratio is just 4.3 kilograms per bhp.

The TT RS Coupé rockets from 0 to 100 km/h (0 to 62.14 mph) in 4.6 seconds; the Roadster needs just a tenth of a second longer. The limited top speed of 250 km/h (155.34 mph) is merely the official figure for both versions; as an option, Audi can increase it to 280 km/h (173.98 mph).

Almost even more impressive is the aggressive pulling power. The maximum torque of 450 Nm (331.90 lb.-ft.) is always available between 1,600 and 5,300 rpm. In addition, the TT RS overtakes without the slightest effort. Last but not least, its engine makes passengers’ skin tingle time and again thanks to its speedy and powerful response, its inspiring free-revving character, and its unmistakably guttural tailpipes: five-cylinder classical music by Audi!

As an uncompromising sports-car engine, the 2.5-liter TFSI is ultra-compact. Just 49 centimeters (19.29 inches) in length, it is ideally suited for transverse installation in the TT RS. And its weight of just 183 kilograms (403.45 pounds) also sets a record. The crankcase is made of vermicular-graphite cast iron. This high-tech material unites the utmost in strength with low weight; it has otherwise only been used for the large TDI engines from Audi. Perfectly placed reinforcements enhance the block’s loadability. The lightweight cylinder head, the pistons, and the connecting rod are lightweight as well as high-strength.

The ultra-powerful five-cylinder engine is extremely fuel-efficient, requiring an average of just 9.2 liters/100 km [25.57 mpg] as regards the Coupé (Roadster: 9.5 l/100 km [24.76 mpg]). Switchable flaps in the intake manifold mix the incoming air in a calculated configuration. Injected at a pressure as high as 120 bar by the common-rail system, the gasoline swirls intensely in the combustion chamber – which in turn cools the walls. This subsequently facilitates a compression ratio of 10.0:1, which is very high for a turbocharged engine. Both of the adjustable camshafts, controlled via chains, also enhance charging efficiency with respect to the air-fuel mixture.