If you like what you've seen so far, now's the time to check the car's paperwork - to note a few details and make a couple of phone calls.

Half a million cars are stolen in the UK each year. If you're conned into buying one, or one with finance still owing on it, you could end up not only losing the car but the money you paid for it. Insurance write-offs may have been in a serious accident so could, if they've not been properly repaired, be dangerous to drive.

Ask to see the car's service records, MOT certificate and its registration document (the V5 form, sometimes called the car's 'logbook').

Never buy a car without a V5 registration document. If the seller is unable to produce it for any reason, walk away.

First check the V5 is genuine by looking for the watermark.

Next check the registration number, car description and chassis number on the form all match the car.

Ask for proof of the seller's name & address and check it matches what's on the form. If buying privately, you should be doing the deal at the address shown on the V5.

To check the car's chassis number matches the V5, look at the car's data plate (often called a 'VIN' plate), normally found under the bonnet. Look particularly closely at metalwork around the plate when you do this to spot signs of tampering. The chassis number should be stamped somewhere else on the car too - often around the driver's side door sill or the base of the windscreen. Look in the car's manual to find where it should be and check all numbers match.

This will help you avoid buying a 'clone' - a stolen car that's been given the identity of a similar, legitimate one that's already on the road. The number stamped on the chassis is harder to alter than the car's number plates or VIN plate under the bonnet.

Next check the MOT certificate - check the details against the car, and check it expires when the seller says. Check the certificate is genuine at www.motinfo.gov.uk. But remember, an MOT is no guarantee that the car's roadworthy. You should have given the car a thorough inspection already to get an idea of its current condition.

Service records: hopefully the car will have a good file of service receipts or, ideally, an up-to-date service record book full of main dealer stamps at the right intervals. A lack of receipts indicates a car that hasn't been cared for and which might prove unreliable. Check the records for who has been doing the servicing, what work has been done and whether anything has had persistent attention but may still be unresolved. If there are old MOT report sheets, see if any warnings of looming faults were noted and check if they've been fixed - or you could be hit for the bill next time around.

KwikTip: always get a car insurance quote from Direct Line too,
as they don't take part in the price comparison websites.

See if the mileage has been recorded on any receipts - old MOT certificates are best for this. If the owner still has them, that's a good sign. See if the mileage has progressed in a normal way over the years, bearing in mind the average is 10,000 miles a year. And check the mileage on the latest MOT certificate against that shown in the car.

Make enquiries: if at a dealer, or if the car has recently changed hands, note the name and address of its previous keeper from the V5. Get their number from directory enquiries if you can and give them a quick call. Ask them if they had any problems with the car, how they used it, why they sold it and what the mileage was when they sold it. It's no skin off their nose to tell you the truth.

For extra reassurance, contact a company that checks the previous history of cars, like Experian Autocheck, The AA or HPI. A dealer should have done this already - ask to see the report. If buying privately, a history check is essential.

It'll tell you if the car has ever been declared an insurance write-off, whether there's any finance still owing on it, whether it has ever been stolen and may even provide mileage information to help check if the car has been clocked.

A check can be done over the phone or online. You'll need a credit card, the car's registration number and its 17-digit VIN / chassis number.

Warranty: find out what's covered and what's not. Does it cover parts and labour? Will anything invalidate it? Would you have to contribute towards a claim - is there an excess? Is there a limit to how often you can claim?

buying a used car: how to haggle >>