There are 1 owner-reported speed control & cruise complaints for the 2021 Mercedes-Benz GLS-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2021 Mercedes Benz GLS450. The contact stated while driving 75 mph with the cruise control engaged, the vehicle decelerated to 45 mph than to 15 mph. On another occasion, while driving 80 mph, the vehicle independently decelerated to 45 mph. There was no warning light illuminated. The vehicle was taken to the local dealer however, the mechanic was unable to duplicate the failure. The vehicle was not diagnosed nor repaired. The contact stated that the cruise control and speed assistance feature provided erroneous information. The manufacturer was notified of the failure. The failure mileage was 3,000.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026