Differences between the GMC Denali and AT4 Trim Levels Photo: GMC We’ve all seen those signature badges adorning GMC vehicles — but what do they signify? The Denali and AT4 trim levels are two of GMC’s sub-brands offered across the model lineup, and they each come with a distinct set of features. Here’s a look at their differences. Denali Photo: GMC Denali models are all about upscale style and luxury. This range-topping trim features leather upholstery, signature seat trims, aluminum accents, and contrast stitching, which serve to make Denali interiors distinct from other trims. They...