The nomenclature employed for the pillars is completely based on their shapes as seen from sides. A – Pillar forms the shape of alphabet “A” and other form “B”, “C” and “D” shape respectively. If the car is a stretched vehicle with additional doors like a limousine creates more B – pillars, they are then named as B1, B2 and so on while moving from front to rear.
The most costly components to repair are vehicle’s roof and door design, so in order to make them withstand crash and meet safety standards A – pillars are given on either side of windshield making use of strong steel alloys. Some give a slimmer and chamfered A – pillars to reduce blind spots (occurring due to blocking of driver’s vision of A – pillar, side rear view mirror and interior rear view mirror) and thereby improving driver’s vision.
B – Pillar is the most complex structure on the vehicle with front door closing on it whilst rear is hinged onto it. Talking about the B (or center) pillar on four-door sedans, the pillar is made of steel welded to roof panel on top and floor pan at car’s bottom. This pillar provides structural support to the car’s roof. There are some vehicles without a B – Pillar which are widely called hardtop are available in nearly all – four door body styles fromsedans to wagons. The cars without B – pillars increase occupant visibility while compromising on structural support and strength. General Motors later started including B – pillars in hardtops thereby broadening the definition of hardtops. The C- pillar is seen behind the rear door while D – pillar is often seen in Station wagons or MPVs. So while naming a pillar if one say, B – Pillar, is missing then it is skipped when naming other pillars. Thereby, showing that the rearmost pillar is called C – Pillar even if B – pillar is missing.