Your rights are different depending on who you are buying from. It's important to know where you stand if things don't go exactly to plan.
f you buy from a car dealer, which doesn't necessarily mean from a showroom you have rights under the Sale & Supply of Goods Act 1979.
The basic rights mean that the car:
Must be of satisfactory quality (taking age into account)
Must be as described
Must be fit for its purpose
Should be free from defects other than those you know about
Should be exactly what you've been told it is
Should do what you might reasonably expect of it (including specific requirements explained to the seller)
If the car doesn't meet these requirements, you do have a short time after buying in which you may be able to reject it completely. To do this, you must stop using the car immediately and contact the dealer. Then you must follow your complaint up in writing and give evidence for any problems, including to any finance company you have used to fund your purchase. You will need to get an independent assessment of the car and possibly, if the rejection is disputed, take legal action to recoup your money.
If you are involved in a dispute with the dealer, you should check whether they belong to any trade associations, what their policies are and whether they are abiding by the rules of the association. Also think about speaking to the Trading Standards department of your local council.
If you do need to take legal action, you can use a small claims court to make small claims of up to £5000. Over this amount you may proper legal representation which could be costly and time consuming. The dealer may offer to repair or replace the car. If you want to get it repaired make sure that you are given a courtesy car or get all travel costs covered while this work is carried out.
The rights you have when buying privately are much more limited. A legal dispute is only possible if the car doesn't match the description the seller has given. Keep a copy of the advert and take it with you when viewing. You should also make sure you are viewing the car at the seller's home rather than in car park or motorway service station, so that you have their address. It is very difficult to prove that a seller knew that something was wrong with the car even if you find that it has been wrongly described.