Rear body panel spar L / R

A Rear Body Panel Spar (Left/Right) is a critical structural reinforcement component within the unibody frame of a Tesla vehicle. Often referred to as a "rail" or "frame member," it is a high-strength steel or aluminum beam that runs along the inner rear quarter of the vehicle, typically from the rear door pillar to the rear bumper area. Its primary function is to provide immense structural rigidity, crash protection, and support for the rear body panel, trunk floor, and suspension mounting points. In the event of a rear or side-impact collision, it is engineered to crumple in a specific way to absorb energy and protect the passenger cabin and battery pack. The "L/R" designation indicates it is a side-specific part (Left or Right).