The next Audi S6 is expected to arrive next year, and powering the new beast will be the twin-turbo V8 from the Porsche Panamera.

The fully camouflaged car was captured in Avant guise undergoing testing. Autocar reports that it will get the 4.0L twin-turbo V8 that rockets the Panamera Turbo from 0-60 mph in about three seconds. In the Panamera Turbo, the V8 makes 550 hp, but the cheaper S6 will likely get a few fewer ponies in the stable. The same engine is also expected to see duty in the S8 and Bentley Continental GT.

While the Panamera's V6 E-Hybrid powertrain could also make it into the S6, the car spied testing doesn't appear to have a plug-in port, just a conventional fuel filler. The V8 also offers more of the muscle car experience than the hybrid, even if that powertrain is no slouch itself.

The new engine will make the S6 handily the most powerful A6 variant, beating the 335 hp V6 of the lesser models. At least until the RS6 arrives.

Expect a more expressive look, matching the A6 models, but not the massive wheel arches or rear diffuser that will likely be reserved for the RS model.