Today I deal with an exception, the first-series Cadillac Sixty Special. Rather than do a year-by-year analysis, the focus is on the styling of the first (1938) model year and the last (1941) where the same body was used.
The Sixty Special's styling was by Bill Mitchell early in a career that culminated in the General Motors styling vice-presidency upon the retirement of Harley Earl. At the time the Sixty Special first appeared, American sedans tended to have awkward, lumpy styling. But the Sixty Special had a nicely integrated lower body where the ample-for-the-times trunk blended into the side panels. But it was the upper body ("greenhouse") that set the car apart. It featured a distinct, all-around separation from the lower part, and its side windows featured light, chromed frames that were distinct from one another -- not visually tied together around the door center posts. These features are best explained in reference to the images below.
The illustration is by Jon Whitcomb who is best known for his portrayals of glamorous women.
The blending of the principal lower body elements is shown clearly in this image. Also note the side window treatment. The car might seem unexceptional to present viewers, but that's because the Sixty Special helped set the pace for future designs by GM and many of its competitors.
Even though it had a distinct body, the Sixty Special's grille, hood and fenders were those used in other 1938 Cadillacs. This component sharing continued to be the case through 1940.
The trunk blending is featured in this view, as is the distinctive three-piece rear window -- a feature carried over through the 1940s.
Sixty Special component-sharing was given a slightly different twist for 1941. Other '41 Caddies had squared-off "suitcase fenders" that terminated next to the front door opening, but the Sixty Special's fenders extended part-way over the front doors. This previewed a styling feature found on GM's 1942 line (aside from senior Buicks, whose front fenders extended to the leading edge of the rear fenders).
Front end styling on 1941 Cadillacs was outstanding, setting themes that were used for years.
Rear wheel opening covers were pretty much standard for 1941.
So why do I claim that the first-generation Sixty Special generally survived the annual facelift procedure? Because the car's distinction was in the body itself, from the cowing to the rear end. This remained essentially unchanged and was as distinctive in 1941 as it was in 1938. Future Sixty Specials never struck me as being nearly as special as those from the first design generation, in part because their bodies differed little from those of other Cadillacs.