2005 Mercedes-Benz SLK 3.5L Petrol · FG55 FRZ

A recurring weakness in the rear sub‑frame combined with persistent corrosion of both rear brake pipes defines the mechanical story of this 2005 Mercedes‑Benz SLK. The 2022‑08‑16 MOT recorded a major failure for an off‑side rear sub‑frame that was “corroded and seriously weakened”, and the same test flagged slight play in the off‑side front wheel bearing. Subsequent tests have consistently shown advisories for corroded rear brake pipes (both nearside and off‑side) and for oil and coolant leaks, while the vehicle has otherwise passed each annual inspection, most recently on 4 November 2025 with only those advisory items remaining. At 138 617 miles the car averages roughly 6 600 miles per year, a mileage level that is typical for a vehicle of this age and does not, in isolation, indicate abnormal wear. The MOT history shows no large gaps in testing, with annual checks recorded from 2019 through 2025, suggesting the odometer reading is reasonably reliable. The steady annual accumulation means consumables such as suspension bushings, brake pads and tyres will have experienced normal wear cycles, but the presence of multiple corrosion‑related advisories points to exposure to moisture or road salt over the vehicle’s life, which can accelerate degradation of metal components beyond what mileage alone would predict. Prospective buyers should inspect the rear sub‑frame for any visible rust, pitting or deformation, especially around the mounting points, and listen for clunking noises when the car is driven over bumps, which would indicate structural compromise. The rear brake pipes, covered in grease and corroded along their length, should be examined for signs of leakage, soft spots, or excessive rust that could lead to brake fluid loss; a spongy or inconsistent brake pedal feel under moderate braking would be a red flag. The oil and coolant leaks noted in the most recent advisory should be checked for drips under the engine bay and for any puddles on the ground after the car has been parked, as even non‑excessive leaks can herald gasket or seal failure that may worsen quickly. The off‑side front wheel bearing’s slight play, although only advisory, warrants a test‑drive assessment for any humming, grinding or vibration that intensifies with speed, particularly when turning left. Tyre condition should be verified against the advisories for sidewall cracking and edge wear on both front and rear tyres; any visible cracks, bulges or uneven tread could compromise safety. Finally, the front fog lights that were recorded as non‑functional and the front brake discs described as rusty should be confirmed as operational and free of severe surface corrosion, as both affect visibility and braking performance respectively. Addressing these specific items before purchase will give a clearer picture of the car’s roadworthiness and the likely cost of remedial work.