2003 BMW Z4 2.5L Petrol · T44 CAC

A twenty-three year old BMW Z4 with 148,608 recorded miles presents a mixed mechanical picture, with the most recent activity on 24 November 2025 showing both a pass and a fail recorded on the same date. The failure items were relatively minor in isolation, comprising a non-functioning nearside front position lamp and a windscreen washer providing insufficient washer liquid, both of which are straightforward rectification items. However, the surrounding advisory record reveals a more telling pattern of age-related wear: a nearside rear tyre worn close to the legal limit on its inner edge, both rear suspension arm pins or bushes showing wear without yet resulting in excessive movement, general underbody corrosion across various components, and brake disc surface corrosion on all four corners. The 2024-12-12 failure introduces more serious concerns, with exhaust carbon monoxide readings exceeding both the default limits after the second fast idle and the manufacturer specified idle limits, alongside a non-functioning rear fog lamp. The subframe corrosion advisory has also recurred across the 2024 and 2025 tests, suggesting a progressive rather than static condition. The annual mileage of approximately 6,461 miles over the vehicle's twenty-three year life sits close to the typical accumulation rate for a car of this age, indicating steady rather than exceptional use. There are no extended gaps in the testing record that would suggest prolonged periods off the road, and the consistent annual testing between January 2024 and November 2025 implies regular operation. That said, a vehicle of this vintage and mileage will have accumulated significant wear on drivetrain, suspension, and braking components through normal use, and the relatively modest annual mileage does not insulate the car from the consequences of age on rubber, plastic, and corrosion-vulnerable components. The pattern of advisories is consistent with a car that has been used consistently but is now displaying the typical mid-life deterioration expected on a roadster of this generation. For a prospective buyer, the recorded advisory and failure items point directly to the components that warrant close physical inspection and a careful test drive. The recurring rear subframe corrosion, even though not yet seriously weakened, should be examined with the vehicle on a lift if possible, paying particular attention to mounting points, suspension pickup locations, and any evidence of flaking or section loss. The rear suspension arm pin and bush wear noted in late 2025 is likely to be progressive, and on a road test the buyer should listen for clonking or knocking noises from the rear over uneven surfaces, particularly on direction changes, and feel for any vagueness in rear wheel location over bumps. The brake disc surface corrosion on all four corners is expected on a car that sees mixed use, but the buyer should check for any pulsing or judder through the brake pedal under firm application, which would suggest disc thickness variation or runout beyond serviceable limits. The corroded front brake pipes noted in the 2024 test should be inspected along their length for any swelling, weeping, or active corrosion, as aged brake lines are a recognised failure point on vehicles of this age. The exhaust carbon monoxide exceedances from December 2024 are a more pointed concern and warrant direct investigation rather than assumption. The buyer should ask for evidence of any catalytic converter or lambda sensor replacement since that test, and on a cold start listen for any rattling from the exhaust system which could indicate internal catalyst breakdown. The engine should be observed from a cold start for excessive smoke from the tailpipe, particularly blue or black smoke, and any irregular idle behaviour or stalling should be noted as it may relate to the emissions issue flagged. The inner edge tyre wear on the nearside rear flagged in 2025 suggests a possible geometry issue, possibly related to the worn rear suspension components, and the buyer should check current tyre wear patterns across both rear wheels for any unevenness. Given the combination of age, mileage, recurring corrosion advisories, subframe surface deterioration, and the emissions failure, this Z4 would benefit from a thorough pre-purchase inspection by a specialist familiar with E85/E86 Z4 models, with particular attention to the rear subframe, suspension bushes, brake lines, and exhaust system.