There are 2 owner-reported electrical system complaints for the 2018 Mercedes-Benz GLS-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
SEATBELT HAD TIGHTENED AND NOT RELEASED WHEN MY BODY MOVES. BRAKES ARE NOT APPLIED. TYPICALLY DURING DRIVING I'M SMALL ENOUGH TO MANEUVER MY HAND DOWN TO RELEASE RED SEAT BELT BUTTON. *TR I'VE HAD TO STOP MY VEHICLE 5-10 TIMES TO RELEASE BELT. I HAVE 2 SMALL KIDS 7/ 11 BOTH ARE 60 POUNDS THEY ARE 4 FEET TALL AND 4'6' 7 YEAR OLD STILL USES BOOSTER I''VE CHECKED BELTS TO THE BEST OF MY ABILITY BUT I'M 110 LBS 5'2' AND HAVE NO MECHANICAL TRAINING OR EXPERIENCE OR CERTIFICATIONS THIS HAS BEEN NOTED TO MERCEDES AND THE PROBLEM IS NEVER REALLY DISCUSSED. THE VEHICLE WAS OPERATING UNDER ALL CONDITIONS NOTED BELOW
TL* THE CONTACT OWNS A 2018 MERCEDES-BENZ GLS450. WHILE DRIVING 70 MPH, THE VEHICLE LOST POWER AND ALL THE WARNING INDICATORS ON THE INSTRUMENT PANEL ILLUMINATED. ALSO, WHEN THE BRAKE PEDAL WAS DEPRESSED, THE VEHICLE FAILED TO STOP. THE CONTACT STATED THAT THE VEHICLE FINALLY STOPPED UPON REACHING A HILL. THE VEHICLE FAILED TO RESTART AND WAS TOWED TO FLETCHER JONES MOTORCARS (3300 JAMBOREE RD, NEWPORT BEACH, CA 92660, (949) 718-3000). THE DEALER DIAGNOSED THAT THE WIRING HARNESS MELTED. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE AND A COMPLAINT WAS OPENED. THE FAILURE MILEAGE WAS 200.
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 26, 2026