Do your homework
Start with the MOT history, not the advert. Check the free MOT record and read the advisories from every test, not just the pass or fail. Advisories are warnings, but they're also your evidence. If the tyres were close to the legal limit last year and still are, it's fair to ask why nothing was done. The legal minimum tread is 1.6mm, and brake pads fail below 1.5mm.
Check the miles and the gaps. Mileage at each MOT shows how the car has been used. A drop between tests is the classic sign of clocking, so walk away unless the seller can prove it. Compare the average yearly miles with the UK figure of about 7,100. Long gaps need an explanation, such as a SORN, so ask the seller.
Compare it with similar adverts. Search for the same make, model, year and mileage, and note the asking prices. Then turn each advisory into a cost you can name, such as tyres or front discs, and ask the seller to take that off the price. Check the history first with the free MOT history check.
At the viewing
Walk round the car with your MOT history open and point out the work it needs. Tyres are the easiest case: the legal minimum is 1.6mm across the central three-quarters of the tread, so a set sitting close to that is a real cost. Brake pads fail below 1.5mm, and worn or pitted discs are common advisories too. Say what you've found, and let the seller hear the evidence rather than your opinion.
Stay calm and let the seller talk. Don't show how keen you are, and don't reveal your top price until you've heard their figure. Ask clear questions, take your time and don't be rushed into a decision on the driveway.
Be ready to walk. Before any money changes hands, check the V5C name and address match the seller's ID, and that the VIN matches the car on the windscreen, door pillar and logbook. If the mileage has dropped between MOTs, that is the classic sign of clocking, so walk away.
Closing the deal
Agree the price and what's included before any money changes hands. Get it in writing: spare keys, service book, MOT certificate and any repairs you've agreed, such as new tyres or brake pads. If the seller promises something, it goes on the receipt.
Ask for a written receipt with the seller's full name and address, the date, the agreed price, the registration, the VIN and the mileage. Check the V5C: the name and address should match the seller's ID, and the VIN should match the car. The V5C shows the registered keeper, not the legal owner, which is why a finance check matters. Remember that car tax doesn't transfer, so you'll need to tax the car before you drive it.
Pay only once the paperwork checks out. Choose a method that leaves a record, and never pay cash without a receipt. Before you pay, run a Full Check (£9.99) to look for finance, stolen and write-off records.