In the GM styling studios, this flamboyant boattail roof was proposed for the popular 1965 Pontiac Grand Prix. 

Bill Michell, the powerful vice president of styling at General Motors from 1958 to 1977, was attracted to bold, dramatic design elements, and a few of these flamboyant gestures would continually reappear during his tenure, often on remarkably different products. One such feature, the tapered boattail roofline, appeared on both the 1963-67 Corvette and the 1971-73 Buick Riviera. (See our feature on the Boattail Riviera here.)

And here’s another twist: As the above photos show, at one point the boattail roof was also proposed for the 1965 Pontiac Grand Prix. And it seems that the idea was fairly serious, as it was still in play late in the product’s development. This full-size fiberglass studio model with the internal GM designation XP-765 was reportedly presented in April of 1963, when production of the ’65 Pontiacs was scheduled to begin in August of 1964. But as we all know now, of course, the boattail Grand Prix was ultimately not approved and the production version featured a more traditional roofline.

As a recurring design theme at GM, the tapered, fastback roofline predates even the Mitchell era, originating with his predecessor, Harley Earl. Two Oldsmobile dream cars, the 1954 Cutlass and the 1956 Golden Rocket, used versions of the boattail, and the 1956 photo above shows the familiar split-window motif on a 1958 Corvette proposal, in pretty much the same form in which it appeared on the production Sting Ray coupe in 1963.

While the roofline of the production Grand Prix wasn’t nearly as radical as the boattail proposal, it wasn’t plain vanilla, either. Grand Prix hardtops at the time (1963-68) featured a rear glass with a distinctive, scooped-out contour (below). Not a standard GM B-body feature, the convex backlight was shared only with the Oldsmobile Starfire and Jetstar I, while at Pontiac it was used only on the Grand Prix.