Audi S8 spotted in final testing phaseWhen the new A8 was released, we all knew an S8 model was going to follow shortly. We can see that model here spotted in a final testing phase with basically no disguise. The quad pipes in back give it away as well as the testing gear attached to it. As we reported last month, the S8 will get a twin turbo 4.0 V8 with about 520 horsepower. This should make it a nice rival for the Mercedes S63 AMG as well as the Alpina B7.