i think there's a bunch of nostalgic folks designing the
porsches....... 
theres something about developing newer, more modern version of an
old classic because it gives an identity to the car. when the new
beetle came out, anyone never even heard of the car would go "hey,
that looks like the vw beetle". likewise for ferraris, aston
martins and evos. if they depart from this design, they might as
well codename it as something else instead of the carrera.