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What 22 owners told NHTSA about the 2018 Mercedes-benz GLS

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (22)Crash / fire / injury (4)Brakes (4)Suspension (4)Electrical system (3)Body & structure (2)Engine (2)Transmission & drivetrain (2)Driver assistance (1)Electronic Stability Control (esc) (1)Fuel system (1)Lights (1)

4 of 22 complaints match · Brakes · clear filters

Dec 5, 2025BrakesEngineDriver assistanceFire

January 2023 - Airbag suspension failed. Replaced by Mercedes dealership. December 2024 - Airbag suspension failed. Replaced by Mercedes dealership. April 2024: First brake failure. The brakes stopped while driving. Repaired. April 2025: Second brake failure. Brakes failed again. Repaired. The mechanic stated the line was too close to the wheelbase, resulting in a pinpoint-sized hole. No warning lights. July 2025: Engine failure - the vehicle experienced a complete shutdown while driving with no warning lights. Vehicle in shop for 6-8 weeks for engine replacement by certified Mercedes mechanic. Post-engine replacement (July - Nov 2025) - Severe oil leaks at left cylinder head, small leaks at right cylinder head. Coolant warnings and overheating despite adequate coolant. Radiator and vent line issues. Active Brake Assist Limited warning appeared. Late November - Vehicle emitted smoke and experienced a small engine fire, observed under hood after stopping. Mercedes dealership deemed car unsafe to drive. During engine replacement wood pieces were found where destroyed motor mounts should have been. Multiple issues with no notice or warning lights.

NHTSA ODI 11703281

Aug 26, 2025BrakesFuel system

Brake brakes are terrible. They have other years that they’ve acknowledge that the break are spongy and at times does not break the GLS has that defect. Also smell of gas fumes inside the vehicle. Please direct me the right way and help me with this issue. The brake issue almost have caused me two major accidents car doesn’t stop mechanic says this is a Mercedes issue You may contact me at [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11683217

Oct 21, 2021Brakes

Took vechicle for warranty repair of the frozen and suck both front calipers to Rallye mercedes dealer, repair was refused, car was noty drivable since brakes were stuck, still was kicked out of the dealership

NHTSA ODI 11437633

Sep 8, 2020BrakesCrash

I WAS ALREADY 90% IN PARKING LINE WHICH IS HANDICAP'S. ABOUT TO STOP RIGHT FRONT OF HANDICAP SIGN, SUDDENLY VEHICLE START MOVING FORWARD WHILE MY FOOT WAS IN BRAKE SO I PUSH LITTLE HARD TO COMPLETE STOP BUT VEHICLE SUDDENLY ACCELERATE FORWARD SMASHING INTO THE BUILDING GLASS ENTRY WALL AND DOOR. I AM SO CERTAIN THAT MY FOOT WAS IN BRAKE. I WANT TO KNOW THAT IS THERE ANY WAY SOMEONE CALL OR VISIT WHERE BODY SHOP TO INSPECT THE VEHICLE SO I CAN ASK MANUFACTURE TO REPLACE MY VEHICLE.

NHTSA ODI 11353649

Working with the data? Download all 22 complaints as CSV · fetched from NHTSA July 20, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2018 Mercedes-benz GLS verdict →