The new Audi lineup already includes one sporty cabriolet - a variant of the ever-popular A5. Now, it's about to gain another: the RS5 Cabriolet. Or at least that is what the current rumor mill is spinning out. And, unlike some of the more flagrant rumors Jim Ellis Audi serving Atlanta is privy to, this one is actually grounded in some highly astute observations.

See, before any vehicle can legally go on sale in the…