So Car writers aren't sure whether or not this black-on-black Audi S5 is an RS5 prototype being flogged ahead of an auspicious release in Frankfurt. But the mag's sources say the BMW M3 coup fighter is most definitely in the works. The tipoff that this may indeed be the RS5 is the array of test equipment arrayed on the S5, which is already a done deal. Could be a last-minute production shakedown? Sure, but who wants to talk about that?