This is a tuff question to answer without turning it into a small book, but I'll try to keep it brief. If I were looking I would not get anything older then one of the 08's, unless I was getting it from a dealership that could confirm all of the tsb's have been done to it. I think a compression test is a must. Try to find out as much about the previous owner as possible, or look for an older individual if buying it directly from a seller. They typically take better care of their cars, but not always. The condition of the rest of the car is going to say a lot about how the previous owner maintained it. Is the interior in good, or poor shape ? If they beat up the interior chances are they neglected everything else as well. If buying from a seller look for where the car is parked, do you see any leaking fluids, or an attempt to clean up the evidence. What does the engine bay look like ? Lastly with these cars start it up, and let it idle for at least 10 minutes to see if there is a smoking turbo issue. I'm sure there might be a few more things hopefully someones else will fill in any of my missing info.
