On the outside, there aren't many changes. The obligatory "Grand Edition" badges will be strewn about, and 450 and 550 versions each have LED headlights. Each version also gets fancy wheels, but the GLS 450 just has 20-inch wheels, while the GLS 550 has 21-inch examples.
It's inside where the Grand Edition really shines. Nappa leather covers both the seats and the dashboard, with the seats getting a diamond-stitched design. It features a light beige and brown color scheme with striped, open-pore wood trim, and standard ambient lighting.
This new GLS-Class trim will make its official debut at the Detroit Auto Show. It will also become available toward the middle of 2018. Mercedes didn't reveal how much the trim level costs.