2005 BMW 750 4.8L Petrol · WN55 DMZ

The most recent MOT test on 2026-08-04 resulted in a failure, marking a significant deviation from the vehicle’s previous history where tests were predominantly passed or only recorded minor issues. Prior to this, the car had passed MOTs with only advisory defects, such as minor headlamp faults, tyre wear close to legal limits, and occasional oil leaks, indicating a generally stable maintenance record. However, the latest failure highlights critical issues—dense blue smoke at idle from the exhaust system, which is a clear sign of incomplete combustion likely due to a faulty fuel injector, injector pump, or ignition system component, and a snapped rear brake cable, which compromises braking efficiency and safety. The presence of a headlamp aim failure also suggests a need for immediate attention to visibility, though this is less critical than the mechanical failures. Overall, the trend shifts from minor advisories to major defects, signaling potential underlying wear or failure progression that warrants urgent investigation. The vehicle’s recorded mileage of 96,246 miles for a 21-year-old BMW 7 Series is unusually low, averaging just 4,583 miles annually—a rate that is far below the typical usage of higher-mileage vehicles in its class. Such low mileage can result from prolonged periods of inactivity, particularly in a luxury car prone to standing corrosion, especially in the brake systems, suspension, and exhaust components. The brake pipe corrosion advisories from 2022 and 2023, along with the snapped rear brake cable in 2025, strongly suggest that the vehicle has been stationary for extended periods, allowing moisture and contaminants to accelerate corrosion in critical braking components. Additionally, the oil leaks recorded over the years may also be exacerbated by standing, leading to degraded engine lubrication and potential long-term damage if not addressed promptly. For the prospective buyer, the most pressing concerns stem from the recent MOT failures and recurring advisories. The dense blue smoke at idle and snapped brake cable demand immediate inspection of the fuel system and brake master cylinder or cable replacement, as these are safety-critical failures. On a test drive, listen for irregular engine noises, particularly from the exhaust or fuel system, and check for a loss of braking response or spongy pedal feel, which would confirm the cable failure. The corroded brake pipes should be inspected for structural integrity, as further deterioration could lead to brake fluid leaks or failure. For the oil leaks, verify that the engine is running smoothly and check for any unusual smoke from the exhaust, which could indicate a burning oil condition if left unresolved. Beyond the immediate defects, the vehicle’s age and low mileage profile necessitate a thorough physical inspection for signs of standing-related damage. Focus on the brake discs and calipers for corrosion or binding, as prolonged inactivity can cause rust to form on the braking surfaces, reducing effectiveness. Check the suspension for signs of stiffness or excessive play in the lower hub bushes, which were noted as slightly worn in previous MOTs, and inspect the tyres for sidewall cracking or perishing, which can occur even at low mileage due to age-related degradation. Additionally, test the 12V battery for full charge capacity, as standing vehicles can suffer from parasitic drain or terminal corrosion, and verify that all fluids—oil, brake fluid, and coolant—are within specification, as fluids degrade over time regardless of mileage. Lastly, review the service history for any missing or outdated maintenance, such as timing belt replacement or spark plug servicing, which are critical for a 21-year-old engine.