Used Car Inspection Checklist: What to Check Before You Buy

What to bring to the viewing

Take a torch, a small magnet or paint-thickness gauge, kitchen roll and gloves. A tread-depth gauge or a coin with a known border width helps with the tyres. Bring a second person, ideally one who knows cars, and this checklist on your phone.

An OBD diagnostic reader is worth taking if you have one. Cheap Bluetooth readers show stored fault codes that a cleared dashboard does not.

Papers and identity (checks 1–7)

1. The VIN on the car (base of the windscreen, door pillar, stamped in the body) matches the registration document. Our VIN decoder shows what the number itself says about the car.
2. The registration documents are originals, not copies; where your country uses two parts, ask to see both.
3. The seller is the registered keeper, or can prove why not.
4. The service book has stamps, dates and mileages that rise steadily; invoices back them up.
5. Inspection reports (MOT, TÜV/HU, ITV, contrôle technique) show a mileage that never falls.
6. The number of previous owners fits the car's age. ADAC advises asking questions when there were many or when someone kept the car only briefly.
7. Two keys are present and both work; recalls and campaign work have been done.

Bodywork and glass (checks 8–15)

Tyres, wheels and brakes (checks 16–20)

If the car wears a non-standard tyre size, check the alternatives with our tyre size calculator.

Under the bonnet, engine cold (checks 21–28)

21. The engine is cold to the touch. If it is warm, ask why.
22. Oil level between the marks and oil that is not black sludge. The UK buyer's guide Carbuyer warns that white or light-brown, mayonnaise-like deposits under the oil cap can mean a failed head gasket.
23. Coolant at the right level, clear and not oily.
24. No fresh oil, coolant or gearbox fluid leaks on the engine or the ground beneath it.
25. Belts free of cracks; check the service book for the timing belt change if the engine has one.
26. A cold start without long cranking, rattles or clatter that lasts more than a few seconds.
27. Exhaust smoke: a brief puff at start-up is normal; persistent blue (oil), white (coolant) or black (fuel) smoke is not.
28. All warning lights come on with the ignition and go out once the engine runs.

Interior and electronics (checks 29–34)

29. Wear on the steering wheel, gear knob, pedal rubbers and driver's seat bolster fits the mileage. carVertical, a vehicle history provider, lists pedal and steering wheel wear among the main signs of a rolled-back odometer.
30. No damp carpets, musty smell or water marks in the boot: leaking seals or flood damage.
31. Air conditioning blows cold within a minute; heater and fan work on every setting.
32. Windows, mirrors, central locking, seat adjusters and infotainment all work.
33. The mileage on the instrument cluster matches the last service record and any oil-change sticker.
34. Airbag warning light behaves normally and the seat belts retract smoothly.

Test drive checklist (checks 35–40)

35. The clutch bites in the middle of the pedal travel, without slipping when you accelerate in a high gear.
36. Gear changes are clean on a manual; an automatic or dual-clutch box shifts smoothly, hot and cold, without jerks or delays. Our guide to ZF gearboxes explains how the main automatic types behave.
37. The car runs straight, and the steering wheel is centred at speed.
38. Braking from speed is straight and free of vibration through the pedal or wheel.
39. No knocks over bumps, no droning that changes with speed (wheel bearings), no whine under load.
40. After the drive: no new warning lights, no smell of hot oil or coolant, temperature gauge in the normal range. On a diesel, ask whether the car regularly makes longer runs; the AA notes that short trips stop the particulate filter from regenerating.

When to book a professional inspection

Some faults only show on a lift or a diagnostic tester. The TÜV-Report 2026 is based on 9.5 million German roadworthiness tests. It found that 21.5% of cars had significant defects, with lighting, brakes and drivetrain the most common problems. The defect rate climbs steeply with age. It ranges from 2.9–17.3% for cars up to three years old to 18.3–40.4% for cars up to 13 years old, depending on the model.

That makes an independent check worthwhile for any car with real money at stake. In 2026, ADAC test centres in Köln and Oberhausen charged from €139 (members) or €179 (non-members) for a basic check with fault memory readout. In 2026 a version with engine test, test drive and bodywork check cost from €169 or €199. The 2026 premium check with exhaust and oil analysis started at €219 or €259. Other ADAC centres priced it by vehicle class, from €89 to €149 for members in 2026.

Before you book, read the model's known weak points on its engine page and compare versions in the specs section. Then the inspector knows what to look for. If you are still choosing a model, start with our list of the most reliable used cars.

Walk-away signals

Some findings end the viewing, whatever the price. Skip it if the VIN, documents or seller's identity do not match. The same goes for mileage that falls between two records, or a service history with large unexplained gaps.

Fresh underseal, welding or filler in the sills or chassis legs is another reason to leave. So are overheating, mayonnaise under the oil cap or white smoke that does not clear. Finally, walk away from a seller who refuses an independent inspection or pushes for a quick deposit.