Motorists who unwittingly buy poorly maintained second hand cars are paying out 238 million pounds a year to have their new purchases fixed, according to a survey from the RAC.

The motoring organisation said almost one in three (29 percent) of buyers fail to spot faults before handing over their cash.

The research by the RAC Vehicle Examinations also found that in more than one in ten cases (11 percent) of mechanical faults, drivers had to pay out up to 400 pounds for repairs. In one in twenty cases (6 percent) the faults were so serious the cost of repair was up to 800 pounds.

A lack of mechanical knowledge were the main reason for buyers ending up with dodgy motors with nearly half (48 percent) of the 1,000 people surveyed admitting they knew little or very little about cars. Despite this only 39 percent had bothered to pay for a professional vehicle examination.

It's easy to be persuaded into buying a bargain. Consumers must approach the business of buying a second hand vehicle with caution to avoid disappointment, said Nick Lindsay from the RAC Vehicle Examinations.

Worryingly 48 percent of buyers spent less than 30 minutes carrying out checks on their potential purchases and 11 percent regretted not getting an expert to check out their choice.

The RAC offered a few tips to avoid the pitfalls:

View the vehicle in daylight and at the seller's home address to confirm it matches with the V5 registration document.

Look for signs of mileage clocking such as worn seats or very tired paintwork.

Check for bodywork rust and make sure the tyres are in good condition.

Take a test drive and listen for strange noises from the engine or suspension.

Check all the keys work and that the door keys match that for the boot.

Ensure the engine/chassis numbers match the V5.

Get the car checked by an expert and check if there is any outstanding finance.