While the A6 Avant 3.0 whizzes along with adequate power, the S6 Avant is a rocket ship. Audi boasts a zero-to-sixty time of 6.5 seconds, with a top speed of 155 miles per hour.
The S6 has a hopped-up version of the all-aluminum V-8 that’s been offered in the A8 for several years. With five valves per cylinder, variable intake valve timing, and a variable intake manifold, it makes 340 horsepower. The V-8 has excellent performance throughout the rev range, though it doesn’t have the sort of massive low-end torque of traditional American V-8s.
Audi’s quattro system is so good at getting the power to the road that full throttle from a standing start doesn’t even yield a tire chirp. The S6 employs the latest version of quattro, which reverts to a 50/50 torque distribution from front to back unless wheel slippage occurs. Some measure of power oversteer is allowed, so dynamically the S6 could be a lot of fun on the track. Because such high speeds are required to explore the S6’s adhesion limits, we didn’t wish to test them on public roads.