If you've been lurking, then the "issues" are readily apparent. Some Stingers, not most by any measure, have annoying flaws. The two most mentioned are various extraneous noises; the paint can have adherence problems: both of these basic areas manifest in many ways. Kia warranties the paint up to 36K miles or three years; so obvious paint quality claims are honored (less clear claims that look like road attrition, not so fast).
The extraneous noises are harder to warranty; but most have been attempted to source and resolve because the bumper to bumper is still in force. And, truth be told, most annoying noises are not resolved at the dealership. Various innovative, creative and ingenious fixes have worked and been shared on here.
Hopefully, the vehicle you select is free of any paint defects: a thorough nose to tail inspection will reveal actual defects as compared to damage. (I've researched this quite a bit, and the odds are heavily in the buyer's favor that their car will start out flawless in this regard).
If your car develops the infamous "hatch lid rattle", there is a lot of advice on this: and nearly all hatch rattles/thumps are resolved with one of the fixes that have been devised (examples; washers installed under the stops to remove play; or wrapping a layer of duct tape around the latch; or, a late one, tightening the hatch pistons which were discovered to be loose).
The other most common extraneous noise or noises come from the sunroof. These are more problematic to track down. And a fair number of complainants have just had to live with it, or a reduced amount of noise. A few sunroofs have been entirely replaced under warranty (e.g.
@westcoastGT); most have been disassembled and/or lubed and/or adjusted (screws tightened, even loosened), bits of foam or hockey tape, etc. in strategic places; all with varying results from no change to complete silence, sometimes for the first time since taking possession of the car. One surprisingly easy fix was pushing up hard on the headliner near the sunroof; and apparently this seated some Velcro up there and the "sunroof rattle/squeak/pop" vanished.
Again, the defects are on a minority of Stingers, even if added together. Most Stingers are like mine; trouble free. I've only had mine in for regular maintenance. And she drives and looks almost as if I drove her away from the dealers last week.
Mechanically, operationally, the Stinger, like all modern Kia vehicles, is one of the most reliable, trouble-free cars out there. This includes the drivetrain, sound system, media center, the wealth of features and tech, the lot. Very few complaints about any of it. And very few TSBs, especially considering how new the car is. And not one of them for anything serious or expensive.
(edit: Oh, yeah, should mention brakes. A repetitive complaint in the US Stingers is the "brake shudder" from pad deposits. Kia replaces pads, resurfaces/replaces rotors, even outside of warranty in a number of cases, as "a good will gesture". But the shudder returns using the OEM pads and rotors. Some are on their fourth set of OEM pads and/or rotors. The fear is that if you replace the OEM with
aftermarket that Kia will deny all subsequent warranty claims. But once you've gone beyond 12K miles in the US, pads and rotors are outside warranty anyway; so you might as well get it while you can; then replace with
aftermarket. Virtually all who complained, once they go
aftermarket, no more brake shudder issues. Kia still has not issued any recall for their apparently unwise choice of pad materials for the US market. Note: my brakes have been perfect for well over 33K miles.)
