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What 4 owners told NHTSA about the 2017 Mercedes-benz Slc-class

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 (4)Body & structure (1)Communication (1)Electrical system (1)Engine (1)

Newest first · 4 complaints

Jan 9, 2026Body & structure

The contact owns a 2017 Mercedes-Benz SLC300. The contact stated that while driving at an undisclosed speed, there was a loud whistling sound coming from the upper panel of the roof. The vehicle was taken to an independent mechanic, where it was diagnosed and determined that the bonding of the upper roof panel had failed and required to be replaced. The vehicle was not repaired, and the contact was referred to the dealer for additional assistance. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for further assistance. The failure mileage was not available.

NHTSA ODI 11709887

Oct 9, 2025

On September 6, 2025 while driving approximately 70 mph, the front roof panel of my vehicle detached completely. This was not only a costly failure, but also an extremely dangerous incident that could easily have caused severe injuries or fatalities — either to myself, my passengers, or other motorists on the roadway. As you are aware, Mercedes-Benz has already acknowledged this precise risk through NHTSA Recall No. 21V197000 / Campaign 2021070010, later expanded under NHTSA Recall 23V854000. These documents confirm that the bonding adhesive used on the front roof panel can deteriorate, leading to detachment. Mercedes has therefore had prior knowledge of this defect and its associated safety hazards. Given that my vehicle has now experienced the exact failure described in these recalls, it is wholly unreasonable for Mercedes-Benz to deny responsibility. This was not normal wear and tear; it was a known, documented safety defect that could have resulted in catastrophic consequences.

NHTSA ODI 11692426

May 15, 2024Engine

Piston 1 broken at 76000 miles. Compleat engine failer

NHTSA ODI 11588987

May 10, 2021Electrical systemCommunication

TL* THE CONTACT OWNS A 2017 MERCEDES-BENZ SLC300. THE CONTACT RECEIVED NOTIFICATION OF NHTSA CAMPAIGN NUMBER: 21V058000 (COMMUNICATION, ELECTRICAL SYSTEM) HOWEVER, THE PART TO DO THE RECALL REPAIR WAS NOT YET AVAILABLE. THE VEHICLE WAS TAKEN TO MERCEDES-BENZ OF HILTON HEAD (155 FORDING ISLAND RD, BLUFFTON, SC 29910) WHERE THE CONTACT WAS INFORMED THAT THE UPDATE WAS NOT YET AVAILABLE. THE MANUFACTURER WAS MADE AWARE OF THE ISSUE AND CONFIRMED THE INFORMATION PROVIDED BY THE DEALER. THE CONTACT HAD NOT EXPERIENCED A FAILURE. PARTS DISTRIBUTION DISCONNECT.

NHTSA ODI 11415793

Working with the data? Download all 4 complaints as CSV · fetched from NHTSA July 21, 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 2017 Mercedes-benz Slc-class verdict →