It’s one of the busiest design studios of any car maker, but Audi’s style centre has been working on yet another new model.This time it’s just a facelift, and it’s the A6 that is in line for a makeover. Having been on sale for three years, the four-ring executive model is due a nip and tuck as it won’t be replaced until 2011.Our exclusive spy shots from Northern Sweden show the revised saloon wearing a light disguise. The facelift will consist of a slightly redesigned front bumper, new rectangular fog lamps and bigger air-intakes left and right of the grille.Still disguised on this prototype are the LED day-time driving lights which debuted on the A4, A5 and all-new A3 Cabrio.