Could that used car be an accident write-off or an HP defaulter? There are simple ways to find out, says James Ruppert

It looked good on paper. A 2002 BMW 318i Compact with a full history and a tempting price. A phone call later the situation changed radically when HPI Limited (0845 300 8916, told me the car had been a category-C write-off. The insurance company had decided not to repair the car, but someone else had decided to, and very badly. HPI posted me a piece of paper confirming all this.

Buying a used car without carrying out a data-check is tantamount to lunacy. HPI offered it first to the car trade and in the 1990s to consumers, but since then many competitors have provided a seemingly similar service, with prices starting at under a fiver. It is important to find out exactly what they offer, because there is plenty you can't tell by kicking the tyres and revving the engine.

According to HPI, 24 out of every 100 vehicles checked have outstanding car finance, and if the loan isn't paid off the finance company will want their car back. Four out of every 100 vehicles checked are written off as a result of damage or theft. Every day 100 stolen vehicles are put up for sale and, if you buy one, the original owner, or their insurance company, will want it back. And number plate and colour changescould be disguising the fact that a car was a write-off or is pretending to be a model it's not. A data-check will reveal that the car you are looking at really is that car, confirming that the registration plate and vehicle number correspond with the DVLA. HPI will tell you if documentation is suspect.

The AA (08706 000 838; also offers its own data-check, with Experian providing the information. Recently it has highlighted the risks of buying cars involved in serious accidents.

Rob Whalley, the managing director for Experian's automotive division, said: "In 2005, 68 per cent of all the cars involved in major accidents could be repaired, but the cost of this was uneconomical."

These were classed as category-C or -D write-offs and, while not dangerous to buy, their market value will be considerably reduced. Car buyers are likely to lose a lot of money if they are sold one of these at full price and later discover it is a rebuilt wreck.

In the worst cases, customers could be buying a car that the insurance companies have classed in categories A or B, which are considered too dangerous to be repaired and returned to the road. However, these cars are still finding their way back.

The AA charges vary because there are discounts for AA members, but range from £34 to £49.99. The cost of an HPI Check is £39.95 if you go online, or by phone it is £42.95. For that you will get full details of any number plates and mileage information, which could reveal if it had been tampered with. They can also alert you to forged or stolen MOTs and registration documents. As for write-offs, if the vehicle has been satisfactorily repaired and undergone an inspection, this information will be provided.

On top of that they (like the AA) supply a Glass's Guide valuation indicating what the car is actually worth. If for some reason the information is wrong you can get up to £10,000 compensation. Both RAC (£24.99, and AutoTrader (£24.99, 08701 993 192) checks use HPI data, but do not provide mileage or valuation. With both HPI and the AA Data Check you get a very comprehensive consultation of the important databases, but some companies seem to offer the same sort of service for considerably less.

At just £4.50 I was tempted to use Reg Check (08707 800 507, whom I could text and contact online. It was easy to do and the response was instant, but, although they identified the car correctly, they had no information about the category-C write-off status of the BMW Compact I was interested in.

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