Perhaps we might be coming to the end of this particular strand. Here are three concepts from Ford/Ghia and GM that show the gestation of the glazed C-pillar.
The last vehicle, the GM, is the most convincing as it shows the floating roof though more importantly, the glazing carrying from the side-glass around the C-pillar. The Fords show a will to glaze the C-pillar yet retaining a small radius from the side to the rear. GM’s stylist had the insight to make the radii from side to front and side to back bigger. It had a dramatic effect on the shape of the wing-to-bonnet as well. Notice how the base of the side glass carries around the A-pillar onto the base of the windsceen. Tesla are still yielding to this urge to this very day on their T-type saloon.
GM liked the sweep of the windscreen around to the side and this appeared on numerous GM cars in the later 80s, particularly the Oldsmobile Cutlass and the Buick LeSabre and Park Avenue. Citroen went with the idea and applied it to the 1989 XM in a slightly less decisive fashion. They did manage to have a full sweep of glass from front to back; neglecting brightwork made the effect less apparent.
Ironically, by 2000 such overt aerodynamicism as displayed on GM’s Aero 2000 concept had gone right out of fashion. Cars were still smooth yet did so without having that soap-bar look. The nose of the Avant Garde looks not unlike the last Nissan Primera though that’s probably accidental. It also recalls, less coincidentally the profile of the XM which was drawn in Oct 1984 by Marc Deschamps.