2006 Audi S4 4.2L Petrol · YH56 AOB

The vehicle passed its most recent MOT on 27 March 2026 at 81,386 miles, with no critical failures, but the tester flagged significant corrosion on both rear upper suspension arms, the subframe, and both rear brake calipers. This marks a clear deterioration from previous tests, where only minor shock absorber casing damage was noted in 2023. The progression from isolated cosmetic corrosion to structural component degradation indicates a maintenance trend that is worsening, not improving. The recorded mileage of 81,386 over 20 years equates to an average of 4,069 miles annually, which is low for its age and suggests limited use. The gap between the 2023 and 2024 tests shows a 213-mile increase, followed by a 2,270-mile jump to 2025, and another 418 miles to the 2026 test. This uneven pattern hints at possible long periods of inactivity followed by concentrated driving, which can accelerate wear on seals, fluids, and suspension components that were not regularly exercised. A buyer must inspect the rear suspension arms and subframe for advanced corrosion, particularly around mounting points and welds, as these are structural elements critical to handling and safety. The rear brake calipers, already flagged as corroded, should be checked for binding, seized pistons, or fluid leaks, as corrosion here often precedes complete failure. The shock absorbers, previously noted with casing damage in 2023, may have deteriorated further — inspect for oil seepage, loose mounts, or uneven ride height. The valve stem damage from 2023 was minor but should be confirmed as repaired, and tyre clearance must be verified to ensure no rubbing occurs under load or steering. Given the age and the recent corrosion findings, a full underbody inspection for rust ingress, especially around the subframe and wheel arches, is essential.