Which component of the vehicle is typically found underneath the roof and can be referred to as an interior trim piece?

The headliner is the component of the vehicle that is found underneath the roof and is indeed referred to as an interior trim piece. It serves several important functions, including enhancing the aesthetic appeal of the vehicle's interior and helping to reduce noise and heat transfer. The headliner is typically made of fabric or other materials and is attached to the roof of the vehicle, giving the cabin a finished look.

In contrast, the windshield is an exterior component that provides visibility and protection from the elements, whereas the pillar is a structural element supporting the roof and connecting the front and rear sections of the vehicle. The sun visor, while an interior component, is designed to block sunlight and prevent glare; it does not cover the entire roof area like the headliner does. Therefore, the headliner distinctly qualifies as an interior trim piece found beneath the roof of a vehicle.