Audi is wrapping up development on the 2012 S6 as our spy photographers have caught two undisguised prototypes in California and Germany.

Our spy photographers have caught two Audi S6 prototypes undergoing testing in California and Germany.

Like previous models, the car is distinguished by an aggressive front fascia, aerodynamic side skirts, and a four-tailpipe exhaust system.  Additionally, the California version has a revised interior with carbon fiber trim, a unique instrument cluster and a three-spoke steering wheel.

Power is expected to be provided by a 4.0-liter V8 engine with 440 PS (324 kW / 434 hp). This is only 5 PS (4 kW / 5 hp) more than the current model, but fuel-efficiency will likely improve significantly.

The 2012 Audi S6 could debut at the Frankfurt or Los Angeles Auto Show, so stay tuned for official information.

Gallery: 2012 Audi S6 spied with carbon fiber interior