A used car inspection is a methodical look at the outside, the inside, the engine bay and the paperwork, followed by a test drive. Work through the same checklist on every car you view, in daylight and with the engine cold, and you will spot most of the problems a seller does not mention.
Take a torch, a coin or tread depth gauge, some kitchen roll and, if you can, a second person. Ask the seller not to start the car before you arrive.
Outside the car
Walk round the car slowly, then crouch and look along each side. Light reflecting off the panels shows ripples and dents better than looking straight on.
- Panel gaps. They should be even all round. Wide or uneven gaps at the bonnet, doors or boot can point to accident repair.
- Paint. Look for panels that are a slightly different shade, overspray on rubber seals or trim, and a rough or orange peel finish.
- Rust. Check wheel arches, sills, door bottoms and the boot lip. Surface marks are common on older cars; bubbling or holes are not.
- Glass and lights. Chips in the windscreen in the driver's view, cracked lenses and condensation inside headlights.
- Tyres. The legal minimum tread is 1.6mm across the central three quarters of the tyre. Uneven wear on one edge can mean the alignment or suspension needs attention. Check all four tyres match in size.
Inside the car
- Wear. Compare the steering wheel, gear knob, pedals and driver's seat bolster with the mileage. Heavy wear on a low mileage car is a warning sign.
- Damp. Smell for mould and lift the carpets and the boot floor if you can. Water in the spare wheel well is a common sign of a leaking seal.
- Warning lights. With the ignition on, the dashboard lights should come on and then go out once the engine starts. A light that stays on, or never lights at all, needs explaining.
- Equipment. Try the windows, mirrors, central locking, air conditioning, heater, wipers, lights, infotainment and every seat adjustment.
- Keys. Count them and test each one. A replacement key can be expensive on some cars.
- Spare wheel or repair kit, and the locking wheel nut key if the car has locking nuts.
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Under the bonnet
- Oil. Check the level on the dipstick. Very dark, gritty or low oil suggests poor maintenance. A creamy residue under the oil filler cap can be caused by short journeys, but it can also point to a head gasket problem.
- Coolant. It should sit between the marks and look clean. Only open the cap when the engine is cold.
- Leaks. Look for fresh oil or coolant on the engine and on the ground where the car was parked.
- Belts and hoses. Cracks, fraying or swollen hoses.
- Cold start. Start the engine yourself. Listen for rattles that fade as it warms up and watch the exhaust. A puff of vapour on a cold day is normal; blue smoke can mean the engine is burning oil and persistent white smoke can mean it is burning coolant.
On the test drive
Make sure you are insured to drive the car before you set off. Try to cover town streets, a faster road and a few bumps.
- Clutch. A clutch that bites very high or slips when you accelerate in a high gear may be worn.
- Gears. Changes should be smooth with no crunching. An automatic should change without jerks or delays.
- Brakes. The car should stop in a straight line without pulling, juddering or grinding.
- Steering. It should feel even, with the car running straight on a level road.
- Suspension. Listen for knocks and clunks over bumps and when turning at low speed.
Check the temperature gauge stays steady and look under the car again once you stop.
Paperwork and the VIN
The paperwork should match the car and the person selling it.
- V5C. The registration certificate names the registered keeper, who is not necessarily the legal owner. Check the name and address match the seller and where you are viewing, and hold the document up to the light to see the watermark.
- VIN. The vehicle identification number is usually stamped at the base of the windscreen, on a door pillar or under the bonnet. Check it matches the VIN on the V5C character by character. If it does not, do not buy the car.
- Service history. Stamps and invoices should show mileages that rise in order. Look for major jobs such as a timing belt where the model needs one.
- MOT history. The record is online, so you do not need old certificates. Compare it with what you have seen. Our guide to MOT advisories explains which ones matter.
What you cannot see on a viewing is outstanding finance, an insurance write-off or a police stolen marker. A full history check covers those for £9.99 and also confirms the VIN matches the registration.
When to pay for a professional inspection
A paid inspection makes sense if the car is expensive, you do not know the model, you are buying at a distance, or you simply do not feel confident judging it. Motoring organisations and independent mechanics offer pre-purchase inspections at different levels of detail, and the price varies with what is included.
An inspector will often put the car on a ramp and check things you cannot, such as the underside and fault codes. It is still a snapshot on the day, not a guarantee. Ask the seller what they know before you book, and our guide to questions to ask a private seller will help you decide whether the car is worth the cost.
Common questions
How long should a used car viewing take?
Allow at least an hour. That gives you time to walk round the car, look inside and under the bonnet, take a proper test drive and read the paperwork without being rushed.
Should I view a used car in the rain or at night?
Try not to. Rain and poor light hide scratches, dents, mismatched paint and rust. If you have to, use a torch and arrange a second look in daylight before you pay.
What if the VIN on the car does not match the V5C?
Do not buy the car. A mismatch can mean the car is stolen, has been rebuilt from parts of other cars, or is not the car the documents describe.
Is a professional inspection worth paying for?
It is worth considering on a more expensive car, an unfamiliar model, or any car you cannot judge yourself. An inspector can spot problems most buyers miss, but no inspection can promise a car has no faults.
Written by James Parry. Last reviewed 11 November 2026. Contains public sector information licensed under the Open Government Licence v3.0.