Audi S4 to return to bi-turbos?

Audi will returned to a forced-induction V6 on its all-new S4 model rather than sticking with the current V8 setup, a new report finds. With the new S5 model filling in the GT spot in Audi's lineup, the German automaker can return the S4 to its roots of a performance tuner car.

The new S4 -- which has been reportedly been circling the Nurburgring -- is expected to use Audi's 3.0L V6 FSI and a bi-turbo setup similar to the one found on the B5 car, not a V8 configuration as earlier reported. However, there is the possibility that Audi could opt for a supercharger setup. Whatever type of induction Audi decides to use, output is expected to total at least 300 horsepower -- matching that of the BMW 335.

It is also expected that the next-generation S4 will use Audi's new Audi's Sport Differential quattro system, which is said to virtually eliminate understeer.

It remains unclear when Audi will take the wraps off of its new S4, but our sources say it will bow at an auto show within the year and could be available in the U.S. as early as 2009.