Pillar (A-D)

Some of the American automobile’s more significant design changes have been reflected in the pillars of a greenhouse.

For ease of discussion, pillars have been alphabetized. An A-pillar is on each side of a windshield. Virtually all contemporary vehicles have B-pillars behind the front doors but in the 1950s through 70s pillarless hardtops were popular. The C-pillar is behind the rear door. Another term for a C-pillar is the sail panel.

Wagons, be they old-fashioned passenger cars, truck-based sport utility vehicles or crossovers, have a D-pillar. So do “six-window” sedans, which are those that have side windows behind each rear door.

In the early-decades of the automobile, pillars were vertical. As aerodynamics took on greater prominence, the A- and C-pillars have been given an increasingly horizontal rake. As cars have become lower, the B-pillar has tended to be angled backward at the top of the window. The D-pillar has changed the least, but in recent years automakers have tried to make crossover vehicles less boxy-looking by exploring new shapes.

At the end of World War II pillar design tended to be fairly homogenous among U.S. automakers. The 1948-50 Packard four-door sedan is representative of that period, with its semi-fastback C-pillar, thick B-pillar and backward-angled A-pillar.

Full fastback designs experienced a boomlet in the late-40s. Hudson invested most heavily with this body style. Four-door models had six windows. The D-pillar shrunk significantly when the rear window was expanded in later models.

For the next decade pillars succumbed to fads that had more to do with stylistic whimsy than safety or practicality. One early deviation from the norm was the “which-way-is-it going” roofline of the 1946-52 Studebaker coupe. The wrap-around rear glass area eliminated the C-pillar (go here for further discussion).

No one copied Studebaker’s wrap-around rear window, but many adopted the swept-back C-pillar of the “Loewy” coupes introduced in 1953. Studebaker didn’t invent the idea but arguably perfected it with an unusually raked A-pillar and teardrop profile. Below is a 1955 President model.

In the first half of the 1950s American automakers began to experiment with wrap-around windshields whose A-pillars were vertical. The 1956 Mercury four-door hardtop shown below illustrates a fairly typical A-pillar during 1955-56. These were sometimes called a “dog-leg” A-pillar because it is angled like a dog’s back legs.

Two-door convertibles had never had a B-pillar. In the late-40s they were joined by two-door hardtops. In the second half of the 1950s Detroit went ga-ga over pillarless body styles, adding four-door hardtops as well as both two- and four-door pillarless wagons.

Of course, hardtops did not have the full pillarless effect unless all of the windows were open. Compare the above Mercury to the 1958 Edsel four-door hardtop below, which has its windows closed.

During the 1957-60 period, A-pillars mostly sloped forward on American cars. In 1959 General Motors gave its entire line a forward-curving A-pillar. Below is a Cadillac.

Not all domestic automakers followed along with this trend. Chrysler offered panoramic windshields, but their A-pillars were swept backward. This offered the practical advantage of not intruding into the passenger compartment. As cars became lower, a vertical or thrust-forward A-pillar could be bumped into when entering and exiting a vehicle.

Chrysler’s approach had another advantage — the A-pillar’s lack of an abrupt angle at the windshield’s base had more structural rigidity.

Chrysler’s approach shows the value of not playing follow the leader. The automaker’s basic design, which was introduced in its 1957 models, was used through the 1964 model year on full-sized Dodge and Chrysler models and through 1966 on the Imperial.

In contrast, GM and Ford’s A-pillar designs during 1957-59 were ditched by 1961. At that point, the industry went back to swept-back A-pillars. They didn’t change all that much for a number of decades.

As an example, below is a Ford Elite from circa 1975. Note the small “opera windows” in the C-pillar, which were popular on larger cars during the 1970s and early-80s.

From the early-50s onward, American cars mostly had notchback C-pillars. Fastbacks made a brief reappearance in the late-60s and early-70s, when they were applied to sporty coupes.

The original Mustang may be the most iconic example of the breed even though it was only a partial fastback. The 1965-66 models were also noteworthy because they did not have quarter windows. As you can see below, by 1969 Ford had switched to both a full fastback and quarter windows.. Go here for further discussion about fastbacks from that era.

In the mid-80s automakers began to give A- and C-pillars a steeper rake. The main rationale was to improve aerodynamics. This can be seen most dramatically on hybrids (go here for further discussion about the 2016 Toyota Prius).

Traditionally, a wagon’s D-pillar has been one of the least distinctive parts of a vehicle. However, as automakers have offered a greater variety of boxy-backed vehicles, designers have been pressed to make them look unique. 

As a case in point, BMW’s i3 visually eliminated the D-pillar with wrap-around windows (go here for further discussion).

Meanwhile, Acura designers gave its 2019 RDX an X-shaped D-pillar. The back part of the X gave the visual illusion of a window but was actually black cladding.