[aerohead]

Curiosity led me to print off the blueprint for the 911 Carrera 2.7.
I scaled it to my stack of 'rooflines' and took a look on the X-ray reader.
The engine air inlet below the backlight is slanted on a 23.5-degree angle.
The 'ducktail' tearing edge lofts the 'body' at that location up to a 17-degree slope.
Extrapolating the contour happens to generate a perfect match the 2013 AST.
Aerodynamicist Hermann Burst's original 'solution' for instability was to add a kammtail roofline, intersecting the 17-degree tearing edge position.
Had this been done, the lift issue would be gone, the car would have lower drag, engine cooling would have been improved, and the higher base pressure mitigate the taillight lense back-soiling issue.
The car would no longer 'look' like a 911, so it was shot down by the Paris Dressmakers.
Fortunately, in the intervening years since 1972, Porsche has incrementally 'raised' the back of the 911 in each new iteration.
Today, Porsche finally has the contour Tony Lapine co-designed with Larry Shinoda, for the Chevrolet Corvair Monza GT of 1962.
GM's head of design,'Wild Bill' Mitchell hated the kammback too!