The present post deals with a minor instance of this, small details creating a theme found on upscale American cars during the early 1980s. Those cars were models of the Cadillac Seville, the Continental and Chrysler Imperial. Some background can be found here. According the the first link above, the somewhat retro theme expressed by the designs did not hold up well in terms of sales.
I dealt with Seville styling in this post, so won't go into detail here.
What concerns us is the sweep of the sharp fold at the aft end of the C-pillar. On the Seville it continues down to the rear bumper, with the trunk lid being inset slightly, creating a distinct tacked-on collection of surface facets.
There were several Continental models at this time. The one shown here has a C-pillar trailing edge that also continues down the side of the car, but only a short way.
The same can be said for this Imperial, though the edge continues down a bit more than half way to the bumper. Like the Seville (but to a much lesser extent), it helps set the trunk off as a distinct element.
Because it's a Continental, a false spare tire shape was placed it the rear of the trunk. This view shows the Seville influence in the area of the C-pillar, rear window and upper part of the trunk.
No faux spare tire here, but the shaping of the rear has a similar feel to the Continental and Seville.