A cold seat, sore hip, hot backrest, harsh glare, or awkward pedal reach is an occupant-comfort problem. Mud, road salt, wet footwear, sand, spilled drinks, and heel wear are floor-protection problems. The cabin may contain both, but a thicker or plusher mat does not become a substitute for seat support or climate control.
Choose a cushion, lumbar support, breathable cover, heater, fan, or shade only when it addresses the documented discomfort. Choose a mat or liner when the goal is to protect carpet. If both are installed, check how cushion height changes leg angle and heel position, then confirm the driver-side covering stays retained and clear of every pedal.