2005 Mazda MX-5 1.8L Petrol · EX05 DFY

Running an NC-generation Mazda MX-5 is generally affordable thanks to the efficient 1.8-litre petrol engine, which typically returns 35–40 mpg in real-world mixed driving. Road tax on a 2005 car in this engine size falls into the higher pre-2006 brackets, so expect to pay around £330 annually in vehicle excise duty. Insurance is usually reasonable — most 1.8 MX-5s sit in groups 25–28, so a typical 40-year-old buyer with a clean licence might pay £350–£500 per year, though quotes vary significantly by postcode and driving history.

However, this particular car's corrosion findings will push maintenance costs above average. Brake pipe replacement, suspension arm refurbishment, and any sill welding will easily run into four figures if a specialist is used. Budget-conscious buyers might consider a garage in a drier region of the UK, as corrosion is markedly worse on cars that have spent their lives near the coast or in regions where road salt is heavily used in winter.

Estimated annual running cost for this vehicle, assuming moderate mileage and including fuel, tax, insurance, and a maintenance allowance for the known corrosion issues: £1,800–£2,400.

The MOT history makes the inspection priorities very clear. Begin with the sills — jack the car up and look along both inner and outer sills for evidence of welding plates, fresh paint over filler, or rust bubbling through. The 2025 test noted significant corrosion on both rear inner and outer sills, so pay particular attention to the rear chassis legs and the area behind the rear wheels. Probe with a screwdriver or tap with a hammer; any thin-sounding metal or flaking rust is a red flag. The sub-frames and suspension arms should also be examined — the January 2025 failure listed corrosion on all four suspension arms, both anti-roll bars, and both sub-frames, which is consistent with the model's known top-three failure reason of corrosion.

Next, check the brake system thoroughly. The vehicle has failed twice on brake pipe corrosion (central pipe in January 2025 and August 2026, plus nearside rear in 2025), which suggests the brake lines have not been replaced. Inspect the full length of all brake pipes for rust, particularly at the unions and clips. The tyres on the 2025 test were noted as perished on both nearside front and offside front — even if they have been replaced since, check the spare and confirm the date codes on the current set. Finally, look at the general bodywork: the August 2026 pass recorded an advisory on the nearside outer sill corrosion, suggesting the issue has been only cosmetically addressed rather than structurally repaired.

For the NC MX-5 specifically, also inspect the rear main seal for oil leaks (a known weakness), check the timing chain for rattle on cold start, and examine the boot floor and battery tray for water ingress — a common NC issue that causes hidden corrosion not visible on MOT tests.