I read an article once about a guy who produced this sort of car drawing for brochures and other advertising materials.  Apparently, they would take a photograph and then cut and spread the plate it was printed on.  They would then use the spread out image as the basis for the drawing.  This would let them portray the car as wider and lower than it really was.  Earlier on, this would let them take a tall, boxy car and make it look sleeker and racier.  For this car, though, the proportions were great already.  I think the drawings of this car look kind of odd - sort of dropped like a low-rider.  They don't seem to have done this for the 1966 brochure.