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What 20 owners told NHTSA about the 2021 Mercedes-benz GLA

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 (20)Crash / fire / injury (2)Engine (7)Electrical system (4)Brakes (3)Fuel system (3)Backup camera & sensors (2)Body & structure (2)Tires (2)Driver assistance (1)Speed control (1)Transmission & drivetrain (1)

3 of 20 complaints match · Brakes · clear filters

Feb 5, 2026BrakesEngine

Component/System: Engine cooling and lubrication system. Coolant was found mixing with engine oil (milky oil), indicating internal engine failure (I was informed it could be oil cooler/housing, thermostat, head gasket, or related components). Vehicle is currently at an authorized Mercedes-Benz dealership and available for inspection. The front left inner lining of my front break pad also "failed" inspection and the other 3 front break pads say "caution" and I never received a notification or warning about my breaks. Safety Risk: Coolant contamination of engine oil can cause sudden engine failure or loss of power without warning, creating a serious safety risk while driving, especially at highway speeds. There was no indication that engine oil was mixing with coolant, check engine light failed to illuminate/ no diagnostic warning illuminated. The condition was discovered incidentally during routine maintenance, which prevented any opportunity for corrective action prior to the failure. Confirmation: The condition was confirmed by an authorized Mercedes-Benz dealership during routine maintenance. The dealership stated the failure was not caused by owner misuse.Inspection: Vehicle has been inspected by an authorized Mercedes-Benz dealership (manufacturer representative). No police or insurance inspection occurred, as there was no accident or external event. Warnings/Symptoms: No check engine light or diagnostic warning ever illuminated. The issue was discovered incidentally after I received a low battery voltage notification and a routine maintenance reminder indicating service was due in approximately 1,000 miles, which I arranged promptly. The manufacturer will not perform full diagnostic teardown to determine the root cause unless I pay approximately $3,000 out of pocket. Link to video: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11715960

Apr 29, 2022Brakes

The contact owns a 2021 Mercedes-Benz GLA250W4. The contact stated that while parking his vehicle when he went to apply the brake pedal, the brakes did not engage. The contact stated that the vehicle then crashed into the wall, however, the air bags did not deploy. The contact stated that the warning light illuminated after the crash indicating that "the brakes are now operational". The contact stated that there was no police report made, however, the 2 passengers did seek medical attention. The contact stated he was able to drive his vehicle home, however, the dealer did have the car towed days later and it remains for repair. The contact stated the dealer advised him to contact the manufacturer, as he did to file a complaint. The failure mileage was 9,429.

NHTSA ODI 11462756

Sep 13, 2021BrakesDriver assistance

Car's brake system slammed on in light traffic with no nearby obstacles. Clear night, light traffic, road dry, moderate temperature. If there had been more traffic, or if the road had been slick, high probability of risk. Dealer has been notified, will not be able to pick up vehicle for a day or two. I did not see any warning lights, heard no warning sounds.

NHTSA ODI 11432715

Working with the data? Download all 20 complaints as CSV · fetched from NHTSA July 19, 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 2021 Mercedes-benz GLA verdict →