There are many ways to ensure that you don't end up buying a used car that will only let you down pretty much straight away, but there is no sure-fire way to guarantee this. Even the best looking cars with the most watertight service histories can let the owner down from time to time. As a buyer of a used car, the only action you can take is to ensure that you take the following steps to stave off the chances of mechanical failure.

First of all, when you are shopping, make sure you ask the used car dealer all the questions you possibly can regarding the car you are interested in. You will need to know information about service history, how long it has been on the market, whether you can take it for a test drive and what kind of guarantee he or she offers.
 
The reaction of your queries will naturally alter according to the dealership you are frequenting and the car you are interested in, but if the dealer seems reluctant to furnish you with the information you require, then it may well be time to walk away from that car and that particular used car dealership as well.
 
I went through at least 10 test drives and countless questions when I was searching for my last used car. Eventually I set my heart on a Used Audi as it had all the right service history information and the test drive confirmed that it was still a great car to drive.