The 2026 Mercedes-Benz AMG GLS 63 4MATIC wins on performance with 603 hp and 3.8-second 0-60 versus the BMW's 523 hp and 4.1 seconds (per manufacturer claims). It also provides a more refined ride via air suspension (MotorTrend comparison). The BMW counters with better third-row space and predicted longevity (Consumer Reports).