Linda McKay, of This is Money, replies: One in three cars has a hidden history, according to vehicle checkers HPI.
That means buying a second hand car can be gamble, as many unsuspecting people have been caught out by unscrupulous sellers who fail to declare finance or accident histories.
But you need not find yourself out of pocket and at risk on the road. I asked our experts for advice on your behalf.
More... ASK THE EXPERTS: 'I live with and care for my mother but I'll be made homeless when she dies' How younger drivers can beat the car insurance trap - and even drive a more exciting car Can you find a better car insurance deal?Gavin Hill-Smith, of the AA, replies: When you're looking for a second-hand car, dealers are generally the safest route. You'll get the maximum legal protection with the least risk.
Buying privately can save you some money upfront, but you won't be protected legally if the car doesn't come up to scratch. It's up to you to ask the right questions and have the car thoroughly inspected.
Your reader should invest in a vehicle history check as background investigations identify nearly 30 stolen vehicles a day.
The last thing the purchaser needs is to hand over cash only later to discover the vehicle has been reported stolen or written off by an insurance company after having been involved in a smash.
Some devious sellers may even resort to ‘cloning’, where the car has been stolen and its original identity hidden.
A history check should tell you if the vehicle has been stolen, has a mileage discrepancy, has been written off by an insurer; has had a plate change which could indicate a dodgy past or if it is subject to outstanding finance.
Any of the above could leave you with either a dangerous vehicle or no car at all.
In the first instance you should check the car documents and verify that the vehicle registration details (V5) and the 17 digit Vehicle Identification Number found on the chassis match that held with information at DVLA.
You have more rights under consumer law if you're buying from a dealer but it's still best to try to go on reputation or personal recommendation.
Owner's clubs and forum sites can be a good source of hints and tips as well as helping you find recommended dealers if you're looking for something specific.
Be wary of anything that seems like a real bargain or has a very low mileage for its age. There are bargains to be had but in general, if a deal looks too good to be true then it most likely is.
When looking over the car, if you’re not confident about what to check, try to take someone experienced with you. You could also consider an inspection of the car (the AA offers a full vehicle inspection).
Also, don't forget that there are always other vehicles out there so don't feel pressured to buy – if in any doubt, walk away.
The AA has comprehensive car buying advice on its website.
Linda McKay adds: Prices for car history checks vary and companies can be found online that charge a minimal sum to do them.
You can check a vehicle MOT for free at gov.uk.
Or for more extensive checks including an inspection are available from the larger motoring organisations such as the AA, RAC or HPI.
Alternatively, if you have a local garage that you trust, you could ask them if they will get one of their mechanics to check the car over for you for a fee.
You should always history check a second hand car, but an inspection could save you a whole lot more in heartache.