They all take maintenance.
Gassers around here are getting high-mileage enough that I'm seeing cam-phasers being changed out down at my buddy's shop. For a mechanic, Simple Enough. Cheap Fix ? No, as the part alone is spendy.
If you have one, or are looking at buying one used, research about Fuel Dilution in Oil, with DI gas motors. It can be an issue, esp. with the way some people stretch out, or just neglect, oil changes. Good quality diesel oil has been designed for a long time to accomodate a certain % of fuel dilution - this is a relatively new issue for modern gas motor oils. Go back far enough (carburator era), and fuel dilution was a big issue - part of the reason FI gas engines lasted longer was getting fuel dilution in the oil under control. And, that was before gasoline became ethanol contaminated.
TDI is the only long life car diesel on the road here (meaning - the newer offerings like Cruze haven't been around long). Once EGR came into play on TDIs, having to decarbon the intake after lots of miles became routine. Possibly, that issue has been mitigated a bit in the latest gen. TDI.
1) Do the research.
2) Buy what you want.
3) Enjoy it.
The Ride Ain't Free, regardless of what you buy.
Rgds, D.