You can stand there inspecting the car all day long but ultimately it's going to be impossible for you to tell how the car runs without running it! It is something you must insist on doing as it can make you aware of any issues with the engine, or the start-up of the car, which could prevent you from making an offer on maby a used porsche.

What do you look for though? Here's our short guide:

Firstly, insist that you start the engine when it is cold. You may need to arrange for this to happen with the owner, but any issues with start-up will be apparent upon starting the engine. Look out for excessive smoke from the exhaust and unusual noises.

A failure to start or a struggle to start would indicate that the car needs replacement parts, and will be another outlay, which if you are strapped for cash could be a definitive issue.

It is expected that there will be a small amount of steam or white smoke from the exhaust, with more being expected on cold days. However if there is excessive blue, white, or black smoke then this would tell you that there is an internal oil leak, head gasket failure or a poorly tuned engine. In any circumstance work will be required.

Listen to the exhaust; if it is unusually and unexpectedly loud, then it is likely that the exhaust has a hole in it, which will require a replacement unit. Any rattling or shaking could indicate that the brackets holding it in place are worn; these will also need replacing, but are fairly cheap.

Finally you must check the power steering, if the car has it of course. Turn it full lock from one side to the other. The majority of the time, most power steering units do emit a small whine, however if this is excessive, or there are knocking, screeching, or bumping noises, then it could indicate an issue with the power steering, which the majority of the time is not cheap to repair.