UK Automotive magazine AutoExpress reports to have spotted an Audi S8 test mule out in the wild in Germany while on a fuel stop. The car in the images (many posted after the link) looks like a run-of-the-mill black A8 with black wheels until they noticed the S-car cue quad tailpipes and upgraded brakes on this car that is most obviously a factory test mule of some sort.
We have it on good word, and the AutoExpress report is consistent with this, that Audi will follow its downsizing trend by fitting the new 4.0T FSI twin turbo V8 in the S8 but we'd doubt that means it'll be down on power from the car's current level of 500. In the lighter and better balanced D4 chassis that will make for one very potent ride.
Check out more photos including shots of the rear exhaust and larger brakes after the jump.