Like many things in life, that bargain second hand car you just purchased can often turn out to be more bother than it's worth. And you may be inclined to think consumer legislation will not protect you because you bought an old banger, but second hand cars must be of a merchantable quality and have an acceptable degree of durability.Prevention is always better than cure and buyers should have a second hand car professionally examined before entering a contract. "It's always a good idea to fork out £100 to £150 on the services of an independent assessor . . . he will spot defects that an ordinary punter would never notice," said Mr Harry Walker, a supervisor with the Automobile Association.He says you should scrutinise the log book and the service booklet to make sure the "one owner" and the "only 20,000 miles" claims are true. It is advisable to phone previous owners who can corroborate or deny the seller's claims."Someone may claim that a car has only done 40,000 miles, but when a car is being serviced a sticker is generally put on the engine stating how many miles were on the clock at the time of service. If the car sticker says serviced at 60,000 miles, well you've discovered that the clock has been tampered with," says Mr Walker.If the logbook or service booklet is missing, you should be extra vigilant because its absence may be intended to conceal the car's previous history.It is an offence to tamper with the mileage clock and it is also an offence to sell or to have for sale a car which has been tampered with in this way or which is otherwise falsely described. The Director of Consumer Affairs has powers to prosecute car dealers who make false or misleading claims to customers.Mr Walker also advises a prospective purchaser of a second hand car to do a search on the car at the Hire Purchase Information Centre. Finance companies generally carry out a search to see if a car is subject to a hire purchase, a leasing or short term hire agreement when they are financing the purchase of a second hand vehicle. However, if you are not borrowing, it is prudent to organise a search yourself.A finance company owns the car until the termination of a hire purchase agreement. That means that if you purchase a vehicle which is still subject to such an agreement, the title to the car will not pass to you.According to Mr Alex Schuster, a lecturer at Trinity College, Dublin, and an expert on consumer law, a second hand car should be as merchantable as is reasonable to expect. "The standard for second hand cars is lower than that for new cars, where people have successful sued for aesthetic defects in the car," said Mr Schuster.The two leading cases on the sale of second hand cars highlight the difficulties in defining what is merchantable for second hand cars. In the first case, the purchaser lost his claim for damages for a faulty clutch which was brought to his attention at the time of sale. The court considered this to be a minor problem which did not mean the car was not fit for its purpose of being driven along the road.In the second case, the purchaser of a Jaguar, which had 80,000 miles on the clock at the time of sale, received damages because the car broke down after a further 2,000 miles. The court ruled that if an engine ceases up within a short space of time after the purchase, this is evidence which goes to show it was not reasonably fit for the purpose for which it was bought, as required by the Sale of Goods and Supply of Services Act 1980.If a second hand car breaks down outside the guarantee period provided by a garage, the purchaser may still have a claim under the Act. "The consumer can still rely on the principle the car should be as durable as is reasonable to expect," says Mr Schuster.Although a consumer can bring a claim to rescind the contract and retrieve the purchase price, it is more usual in the case of second hand cars to sue for damages.Section 13 of the Act states that there is an implied condition at the time of sale that the car must be free from any defects which would render it a danger to the public, including persons travelling in the vehicle.This section seems to be an exception to the privity of contract rule and enables passengers and people who borrowed the car to sue the retailer for personal injuries due to the defective state of the car.