2010 Audi S4 will be powered by a supercharged V6 engine

First rumors said the 2010 Audi S4 would share its powertrain with the S5. But this rumors are incorrect as the 2010 S4 will be powered by an all-new forced-induction 3.0-liter V-6 that will generate something close to the 340 hp.

The reason is quite simple: fuel economy. Audi’s strategy is to deliver comparable or improved overall performance by toeing the line on weight and maintaining power output by using forced induction on a smaller displacement engine. Doing so will boost a manual transmission S4’s fuel economy on the European cycle to 23.3 mpg compared with only 19.4 mpg for the V-8 S5. That’s an efficiency gain of 20%.

A less powerful, 290-hp, 310 lb-ft version of the engine will be the base offering in the A6 Quattro, replacing the 3.2-liter V-6. Known as TFSI, which in the past has been Audi’s internal moniker for four-cylinder turbos, the new engine may be referred to as the 3.0T in the model name, possibly indicating a twin-charged system using both a supercharger and a turbocharger. While Volkswagen has a “twincharger,” Audi has not yet offered such a system. At the very least, we expect the new V-6 to be supercharged, although what will allow the S4’s version to generate 50 or so more horsepower is still a mystery.

Audi will debut the 2010 S4 this autumn, probably at the Los Angeles Auto Show.