Most mechanics will do a complete check up and tune of the engine as part of tracking this problem and it’s a good start, because a new set of spark plugs and plug leads might just fix this problem. But that won’t always be the case. As such, you could be looking at a dud sensor somewhere in the engine bay that is telling the on-board computer to shut things down or, at least, not providing the computer with enough information to keep it all running. For this reason, an electronic scan of the vehicle should also be carried out at the same time to see what fault codes are cropping up.

A prime suspect for this behaviour would be what’s called the engine’s stepper motor which is a small electric motor that controls the throttle body and, therefore, the car’s idle speed. If this motor is maladjusted or faulty, it could cause the engine to either idle roughly, too slowly, or stall altogether. But have the scan done before rushing out to spend money on parts that may or may not be the problem.

It's not possible to predict what might or might not happen to any car in the future, all you can do is make sure as best as possible that it is in good condition and has been properly maintained. The Mazda 6 is a sound choice, and the one you have your eye on seems to tick all the boxes. I wouldn't be concerned about the mileage; with the reliability of the current crop of Mazdas you could confidently look forward to many years of trouble free motoring.

You need to have an independent body repair person evaluate your car with the objective of determining the reason it's rusting. Graeme Cuthbert is one specialist who assists owners in resolving issues like yours. He can be contacted on 0422 444 335.