2006 BMW Z4 2.5L Petrol · AV06 KDX

The most recent MOT test on 16 December 2025 resulted in a pass, although this followed a failure just four days earlier on 12 December 2025 caused by the engine management indicator lamp being inoperative or indicating a malfunction. The failure was remedied for the subsequent pass, but the underlying MIL issue and the advisories carried over from that earlier test warrant close attention. Across the recent history the vehicle shows a pattern that is broadly stable rather than dramatically worsening, yet there is a clear and consistent record of fluid seepage from multiple sources including the engine, gearbox prop shaft oil seal, and differential, alongside recurring corrosion advisories on rear brake pipes and flexible hoses. The major exhaust lambda failure in December 2024 and the driver's door cannot be opened from outside failure in the same test are also worth noting, as lambda sensor faults can indicate catalyst degradation, air leaks, or fuelling irregularities on these engines, and a door mechanism fault can recur if the latch or cable has worn. The recorded mileage of 134,286 miles on a 2006 vehicle equates to roughly 6,700 miles per year over its twenty-year life, which is broadly typical for a car of this age but sits at the lower end of average and suggests the vehicle may have experienced periods of lighter use or standing. This is particularly relevant for a Z4, which is often used as a second or leisure car rather than a daily driver, and standing for extended periods tends to accelerate corrosion on brake components, flat spots or sidewall perishing on tyres, and deterioration of fluids and the 12V battery. At this overall mileage, consumable items such as suspension bushes, coil springs, shock absorbers, clutch, and engine ancillary drive components will have seen significant wear, and the recurring offside front shock absorber advisory from 2020 suggests dampers may now be due for replacement. A prospective buyer should pay particular attention to the persistent oil leak advisories, which have appeared at every MOT since at least 2020 from various locations including the engine, differential, and gearbox prop shaft seal. On inspection, look for fresh oil residue on the underside, check the oil level on the dipstick, and ask when the last major engine work was carried out, as ongoing leaks can mask consumption issues or indicate failing gaskets and seals. Listen for any irregular idle, misfire, or hesitation that could relate to the recent MIL lamp and lambda sensor fault, and verify the engine management light functions correctly with the ignition. Examine the rear brake pipes and flexible hoses carefully for corrosion and rust, particularly where they run along the suspension arms, as the recurring advisories suggest these are deteriorating and may soon require replacement. On a test drive, listen for suspension clunks over uneven surfaces, feel for any brake shudder or pulling that might indicate binding calipers or warped discs from standing, and check for any warning lights remaining after startup. Beyond the recorded advisories, a twenty-year-old Z4 with this mileage should be inspected for age-related concerns not necessarily captured in the MOT record. Tyres should be examined for sidewall cracking and perishing even if the tread depth appears adequate, as age-hardened rubber can fail suddenly. Inspect the brake discs for surface rust and check whether the calipers release cleanly, as standing use commonly leads to binding and uneven pad wear. Verify the condition and age of the 12V battery, and confirm the service book stamps for time-based items such as coolant, brake fluid, and spark plugs, since calendar degradation of these fluids occurs independently of mileage. Finally, examine the folding roof mechanism if fitted, check for water ingress in the boot and footwells which is common in this model, and look for any corrosion around the rear subframe mounting points, which is a known weakness on E85 and E86 Z4s.