You might be short on answers as the US version isn't the same as the European version.
I believe the US version uses the 1.4 Multiair engine, which is basically a 1.4 FIRE bottom end with the Multiair cylinder head.
There has been a few problems with the Multiair units on both the twin and four cylinder engines.
It adjusts the valve timings with solenoids working to change a fluid link between the cam and the inlet valves. This fluid link is engine oil, so it's reliant on the right grade and quantity of oil.
Some have had problems with the solenoids failing and the replacements are quite expensive, but it's not a certainly, many don't suffer.
Make sure it runs without misfires and has a solid service history.
I also think the auto gearbox is a full torque convertor rather than the Dualogic, robotised manual we get this side of the pond. I seem to remember there was a recall on certain cars about them rolling away in park.
The 500 does suffer a few other issues.
The door handles can snap off and the wiring into the top of the tailgate can break.