When you buy a used car, you should always check its technical condition to avoid unpleasant surprises and costly repairs. The purpose of a pre-purchase inspection is to check the varnish layer thickness and the basic car systems, such as the braking, exhaust, steering and cooling systems. In addition, you will have the on-board computer checked for errors. The inspection also covers the suspension and, what's particularly important in the case of diesel engines, the turbo-charging system, which is frequently a source of problems for the purchaser. The AC system will be inspected in terms of its cooling efficiency and checked for leaks.