Known APK problem
Mercedes-Benz C-Klasse S204: structural rust
On the Mercedes-Benz C-Klasse S204 the APK inspector finds structural rust problems 3.3× as often as on cars of the same age: at 13–15 years 1.2%, against about 0.4% nationally.
Window: Oct 2025 – Sep 2026 · Updated: 16 Oct 2026
What is it?
Rust through sills, floor or suspension mounts. Often expensive, and sometimes not worth repairing.
How to check it at the viewing
Look under the sills, in the wheel arches and at the suspension mounts, and press on suspicious spots. Watch for fresh sealant or new underbody coating.
Ask the seller: Has any welding been done on the floor or sills, and by whom?
By age
Share of inspected Mercedes-Benz C-Klasse S204s with this defect, compared with all cars of the same age.
| Age | Type | C-Klasse S204 | National | Difference |
|---|---|---|---|---|
| 11 – 12 years | A | 0.4% | 0.2% | 2.5× |
| 13 – 15 years | A | 1.2% | 0.4% | 3.3× |
| 13 – 15 years | C | 0.3% | 0.1% | 2.9× |
| 16+ years | A | 1.3% | 1.2% | 1.1× |
| 16+ years | C | 0.6% | 1.0% | 0.6× |
A = structure, safety or costly mechanics; B = fail, usually simple; C = advisory. An age is missing when this defect is not among the most common there.
Comparable cars at 13–15 years
| Model | Structural rust | Vs. national |
|---|---|---|
| Mercedes-Benz C-Klasse S204 | 1.2% | 3.3× |
| Daihatsu Cuore (L276) | 0.3% | 3.8× |
| Citroën C4 Picasso I | 0.4% | 1.0× |
| Volkswagen Scirocco III | 2.1% | 6.0× |
Looking at a Mercedes-Benz C-Klasse S204? Check that car
Enter the plate and see the APK history, open recalls and how this car compares with other Mercedes-Benz C-Klasse S204s of the same age.
All weak spots of the Mercedes-Benz C-Klasse S204 · Structural rust: which models more often · Checklist for this model
Frequently asked questions
Does the Mercedes-Benz C-Klasse S204 often have structural rust problems?
Yes, more often than average at the APK. At 13–15 years the inspector found a structural rust defect on 1.2% of inspected Mercedes-Benz C-Klasse S204s, against about 0.4% of all cars of the same age (3.3×). Source: RDW Open Data, Oct 2025 – Sep 2026.
How do you check the structural rust on a used Mercedes-Benz C-Klasse S204?
Look under the sills, in the wheel arches and at the suspension mounts, and press on suspicious spots. Watch for fresh sealant or new underbody coating.
Repair indication: small, medium or large. An indication of the usual repair, not a quote: the real cost depends on the car, the cause and the garage.
Source: RDW Open Data (CC0), analysis CarXray.nl. 6,857,004 inspected passenger cars aged 3 years and older, Oct 2025 – Sep 2026. Each car counts once. How we know