2009 Audi S4 3.0L Petrol · NA59 TLF

Corrosion on the rear sub‑frame and a suite of coil‑spring rust advisories dominate the MOT history, signalling a persistent structural and suspension‑related risk that has not been resolved over successive years. The most recent test on 12 December 2025 recorded a pass but repeated the same rear‑sub‑frame and rear‑coil‑spring corrosion notes, added an oil‑leak advisory on the near‑side rear, and noted the near‑side front coil‑spring as corroded. A single failure in December 2024 related only to headlamp aim, while earlier tests show a steady accumulation of corrosion advisories rather than any trend toward improvement. At 81,868 mi the car averages roughly 4,800 mi per year, well below the typical annual mileage for a 2009 model. Such low utilisation often coincides with periods of prolonged inactivity, which can accelerate rust formation on chassis and suspension components, especially in damp climates. The modest mileage does not necessarily equate to reduced wear on wear‑items such as tyres, brakes or bushings, but it does suggest that any deterioration observed is more likely linked to corrosion and ageing rather than high‑stress usage. Prospective buyers should give the rear sub‑frame a thorough visual and tactile inspection for any signs of deep rust, pitting or loss of metal thickness, particularly around mounting points and the rear axle housing. On a test drive, listen for clunking or knocking over bumps, feel for any looseness or wandering in the rear steering response, and check that the rear wheels remain steady under hard braking. The coil springs—both rear and front—should be examined for surface rust, cracks or broken coils; excessive rust can compromise spring integrity and lead to uneven ride height or handling quirks. The near‑side rear oil‑leak advisory warrants a close look at the differential housing and surrounding seals; any fresh oil spots on the under‑tray or a persistent oily film could indicate a leak that may affect lubrication and ultimately drivetrain reliability. Additionally, the recurring advisory about windscreen washer fluid being marginally sufficient, the defective near‑side wiper blade, the split fuel filler‑cap seal and the slightly damaged outer walls on the front tyres all merit verification. Ensure the washers dispense a steady spray, the wiper blade makes full contact without streaking, the fuel cap seals tightly to prevent vapour loss, and the tyre sidewalls are free of cuts or bulges that could develop into a failure under load. Finally, confirm that all exterior lamps—including the registration‑plate lamp and the corrected near‑side headlamp aim—operate correctly, as any lighting defect will cause an immediate MOT failure.