Hi Gerald,

The biggest things to look out for on that car will be the timing chain and the DSG gearbox.

On start-up and when idling there should be no obvious rattling from the engine (admittedly it may take a mechanic to listen out for that), indicating an issue with the timing chain - same for 'engine check' or other warning lights staying on when the engine is running.

The gearbox requires oil changes regularly so make sure there is evidence of that and take it for a drive to see how smoothly it shifts gears. Ideally you'd try a few examples of the same car from a few sellers so you know which is a good one. 

Because the above jobs are expensive, insist on a service and maintenance history, especially if the car has higher mileage.