The Mercedes-Benz GLS should be practical enough for family use if its cabin layout suits your passengers. Useful size figures include 2025 GLS 450 4MATIC FL: 5209 mm; 2025 GLS 450 4MATIC FL: 2157 mm; 2025 GLS 450 4MATIC FL: 1823 mm; 2025 GLS 450 4MATIC FL: 7. Wheelbase and seating matter most day to day because they influence rear-seat comfort, child-seat friendliness and how relaxed the car feels on longer trips.