Running a Roots-style supercharger that sits between the cylinder banks and operates at a maximum 24.7 psi, the V6 cranks out 333 hp at 5,500 rpm. This is down 11 hp from the third-generation S4’s naturally aspirated 4.2-liter V8.
But the blown V6 also delivers 22 lb-ft more torque than the V8, an impressive 324 lb-ft being released between 2,900 rpm and 5,300 rpm. So there is no great hardship in the loss of two cylinders and 1.2 liters of displacement.
It is sufficient, Audi claims, for an official 0-to-62-mph time of just 5.1 seconds– 0.8 second less than the old S4 and just 0.2 second shy of the time Audi quoted for the last RS4. A more-telling indicator of real-world performance, however, is the 50-to-75-mph fourth-gear time of just 4.4 seconds.
That is quick by any standard and reflects the effectiveness of the V6’s prodigious torque in shifting the S4’s 3,637-pound curb weight. Top speed is still limited to 155 mph, but there is little doubt the new Audi would haul beyond this if left to run all the way to its 7,000-rpm cutoff in top gear.
What is even more impressive is that the S4’s supercharged V6 achieves all this with 27 percent better fuel economy than the V8. Audi puts the combined fuel-economy rating for the new S4 at 24.9 mpg.