Automotive Trunk Side Trim segmentation by type distinguishes three primary material families: injection‑molded thermoplastic, stamped or forged metal, and emerging composite structures such as fiber‑reinforced polymers. Thermoplastic trims, typically ABS or PP, account for the bulk of volume because they combine low unit cost, design flexibility, and compliance with weight‑reduction targets. Consequently, this sub‑segment contributes roughly 65 % of total market revenue. Metal trims—often aluminum or high‑strength steel—serve premium models where surface finish and perceived durability are valued; they represent about 20 % of the market, reflecting higher per‑unit pricing but limited application breadth. Composite trims, leveraging carbon‑ or glass‑fiber reinforcement, are gaining traction in electric‑vehicle platforms where stiffness‑to‑weight ratios are critical; they currently capture near 15 % of revenue but are projected to accelerate as OEMs expand lightweighting programs. The delineation of type therefore clarifies cost structure, OEM preference, and growth vectors within the broader Automotive Trunk Side Trim market. These proportions also influence supply‑chain allocation and investment decisions across Tier‑1 suppliers.