The GMC Terrain's rich, premium interior is influenced by industrial sculpture and exudes refinement exemplified by contrast stitching and fine materials that create a structured look throughout the cabin. A "floating" center stack, highlighted by warm ambient lighting, houses a multitude of ergonomic comfort and convenience controls.

The GMC Terrain also features great attention to detail, with smart use of storage space and compartments that are suitable for a variety of items. They include an oversized glove box; a closed storage area in the instrument panel above the center stack; a closed storage compartment under the center armrest large enough for a laptop computer; and two-tier storage in the doors.

GMC Terrain's seats were developed to provide outstanding comfort and the standard MultiFlex sliding rear seat can be moved fore or aft nearly eight inches (200 mm), providing increased passenger comfort or greater rear cargo capacity. The 60/40-split rear seatback offers additional configurations for passengers and cargo; and the rear cargo area offers 31.6 cubic feet (894 liters) of storage, as well as one of the GMC Terrain's four auxiliary power outlets.