The best thing is to buy a brand new car or an unregistered if you can afford it. If you are planning to buy a used car here are a few tips:
Insist on the valuation by a third party. If you want to lease the car the finance agency will want this valuation anyway. This will give you a pretty clear picture of the cars history, mileage done, number of owners etc and the present market value. There is a " forced sale value" this is the actual value if you want to sell this car.
Get a good mechanic whom you trust to go over the whole engine and body of the car.
Go for a good run ( not a short one) if you are really interested to buy the car.
With the technology available today the car can really LOOK GOOD but the troubles will start after you purchase the car.
Never be in a hurry to purchase and close the sale. Look around find out prices from other sources. Go on the net and find out details of the model and also prices.
However, honest and gentelmanly the car sales person may look they are waiting to make a killing so dont get duped. There are many car sales of repute so better to go and buy from reputed ones and not from the mushroom fly by night car sales.