Compared to the images of the regular A6 model spied in February during cold weather testing in northern Europe, these images are significantly clearer, giving us a better look at the car's detailing and surfacing.
Audi, though, has kept the same level of camouflage on this latest prototype.
As you'd expect, the S6 sits lower to the ground and features bigger wheels with lower profile tyres. Although the front fascia looks the same as the regular A6 prototype, we expect to see at least detail changes and a sharper chin spoiler on the production version.
From behind there's no mistaking the S6 for an A6, thanks to the S model's four exhaust tips.
Under the bonnet, the S6 could feature the new Porsche-developed 2.9-litre twin-turbo V6. This engine made its debut in the second-generation Panamera, and in that car it produces 324kW of power and 550Nm of torque.
Despite featuring a smaller displacement and fewer cylinders than today's 331kW/550Nm 4.0-litre twin-turbo V8, weight savings from the more compact engine, and a lighter body and platform should see performance improve.
The current S6, with a standard seven-speed dual-clutch transmission and all-wheel drive, is capable of reeling off the 0-100km/h standard in 4.4 seconds.
Both the A6 and S6 are expected to make their debuts in 2018, although the S6 will likely trail its bread-and-butter siblings by a few months.