2016 BMW 420 2.0L Diesel · BG66 AAE

The latest MOT test on 2025-09-20 returned a passing result with four persistent tyre wear advisories, all indicating that the inner edges of the front and rear tyres are approaching or have exceeded the legal minimum tread depth of 1.6mm. These advisories are consistent with uneven tyre wear patterns, which may suggest misalignment, incorrect wheel balancing, or suspension geometry issues that have not been fully addressed. The recurrence of these advisories over the past three MOT cycles indicates a maintenance trend that remains unresolved rather than improving, as the same defects persist despite previous tests. While the vehicle has passed each inspection, the repeated warnings suggest that the underlying cause of the tyre wear is not being effectively mitigated, which could lead to further tyre failure or compromised handling if not rectified promptly. The vehicle’s recorded mileage of 69,682 miles at the time of this assessment represents a moderate annual usage rate of approximately 6,968 miles per year, which is typical for a ten-year-old BMW of this class. The consistent mileage accumulation over the years reflects regular, albeit not necessarily aggressive, driving patterns. However, the presence of undertrays in multiple MOT tests from 2022 onwards—particularly when combined with the tyre wear advisories—may imply that the vehicle has spent extended periods stationary, potentially leading to corrosion-related issues such as brake disc binding, suspension component degradation, or fluid degradation from stagnation. Without further evidence of high annual mileage, the wear on consumables like brake pads, suspension bushes, and seals could be more pronounced than expected, warranting closer inspection during a test drive. Given the recurring tyre wear advisories and the installation of undertrays, the prospective buyer should prioritise a thorough inspection of the suspension system and wheel alignment. During a test drive, listen for unusual clunking noises from the rear suspension, which could indicate worn or broken suspension bushes or coil spring damage. Check for uneven tyre wear patterns beyond the advisories—such as cupping or directional wear—which may reveal misalignment or steering system issues. Additionally, inspect the brake system for signs of binding calipers, corrosion on discs, or excessive heat discolouration, as prolonged standing under undertrays can accelerate these problems. If the tyre wear is confirmed to be due to alignment or balancing issues, corrective action should be taken immediately to prevent further tyre damage and potential handling instability. For the broader vehicle inspection, focus on fluid levels and condition, particularly the brake fluid, coolant, and differential oil, as stagnation under undertrays can lead to degradation over time. Check the battery terminals for corrosion or loose connections, and verify that the 12V system is functioning correctly by testing lights, windows, and power accessories. Inspect the exhaust system for leaks or structural integrity, as corrosion from prolonged exposure to moisture can compromise exhaust components. Finally, examine the tyres for signs of sidewall cracking or perishing, which can occur even at moderate mileages due to age-related vulcanisation breakdown. If the vehicle has been stored in a damp or poorly ventilated environment, internal rust in the chassis or underbody may also be a concern, though undertrays may have mitigated some of this risk. A comprehensive inspection should also include a visual check of the engine bay for leaks, fluid contamination, or signs of overheating, as well as a test of the engine’s performance and emissions compliance, given the vehicle’s age.