Audi Quattro Concept – Click above for high-res image gallery

We knew Audi was up to something when it invited us to drive the super-hot Quattro concept late last year. The coupe, currently based on the RS5 architecture, pays homage to the original Ur-Quattro from 1980, and by inviting the media to drive the delicate concept, Audi wanted to show us how serious it is about someday offering a production version.Now, Inside Line reports that a decision about whether or not the Quattro will get the green light should come in September, before the 2011 Frankfurt Motor Show . Stephan Reil, head of Quattro GmbH, admits that the final decision about whether or not Audi will build the Quattro concept has indeed been delayed, but that he is "optimistic" about the concept getting the green light.Reil told Inside Line that, if produced, the Quattro would be a low-volume product with a production run of around 500 to 1,000 cars. Part of the Quattro's goodness is its focus on lightness, and with a target weight of only 3,086 pounds, plenty of exotic (and expensive) materials will need to be used in the car's construction.Furthermore, the RS5 powertrain will need to be revised quite extensively, with Reil citing that the Quattro will need to be more powerful, and that the engine will have to be mounted longitudinally rather than transversely. Even so, Reil said that if given the green light, we could see a production Quattro in about two to three years. Here's hoping.