What Are A-, B-, C- and D-Pillars in a Car?
In the case of cars, “pillars” refer to roof pillars, and they’re lettered front to back. A-Pillars straddle the windshield, B-Pillars are in the middle of the passenger compartment (just behind the front doors) and C-Pillars are those at the rear of the passenger compartment.
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Some might also refer to them as front, center and rear pillars, but that can get a bit confusing when you add station wagons and SUVs into the mix, as “rear pillar” becomes a bit ambiguous. With roofs that run all the way to the back of the vehicle, the rearmost pillars on station wagons and SUVs are referred to as D-Pillars. On specialty vehicles that have more than one B-Pillar — such as limousines — they’re labeled B1, B2 and so on.
Why Do You Need to Differentiate the Pillars?
Perhaps the most likely reason for differentiation is to make parts easier to identify for the consumer. You might read a review of a car indicating something to the effect of, “The A-Pillars are very thick, blocking your view.” This would mean that the front roof pillars are wide enough to obstruct visibility of the front corners. This can be an issue when pulling left out onto a cross street or when pedestrians walk across the street in front of your car.
Supporting this context is that visibility has become a much larger issue in recent years. If you look at many cars from the ‘50s, ’60s and ‘70s, their roof pillars often appear spaghetti-thin by today’s standards. That was great for visibility but not so much for rollover protection in a crash. Furthermore, many cars during this period were “hardtops,” meaning they had no B-Pillars behind the front doors; when you opened all four side windows, they left a big hole. Again, great for visibility — and appearance — but not great for roof support.
Back in their day, hardtops — offered as two-doors, four-doors and even station wagons — were considered more upscale than sedans, which had B-Pillars. Today, due to safety requirements, hardtops have all but vanished, but the hardtop look lives on. This is demonstrated by the number of vehicles that have black B-Pillars, often with chrome trim surrounding the outside of the window area. Some of today’s SUVs use the same technique in the back, hiding the D-Pillars.
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