If you look at Naj's photos of the "notch area" in primer, you'll see a wonderful and wonderfully complex set of compound curves--enough to foil a skilled tool and die maker. This is sculptural, and this is the work of Paul Bracq. Take a look at the same area on today's latest SL's and you'll see homage to the past.
As his story goes, when the car was being designed (on paper), the model builders were not able to duplicate in clay, his vision in this area. While they were skilled, certainly, they were not sculptors or artists of the caliber of M. Bracq. This is when he rolled up his sleeves, and got dirty himself, sculpting this area in clay so that they could eventually make the tooling.
He told a similar story when working on the first 3-series BMW, one of his other masterpieces. At one point, he says, he was working on a plaster 1:1 model to sculpt it to his vision. It was late, and he was covered head to toe in plaster dust, looking like a ghost. The head of BMW came in to the studio (it was a small company back in the early 1970's) and asked the ghost if he might know where Paul Bracq is. "I am Paul Bracq, sir!" was the answer.
One of Paul Bracq's great skills is in sculpture, and the ability to actually craft in 3D what he thinks, with the in between step of 2D on paper.