The issue was exacerbated by customers opting for cheap gasoline and neglecting the use of PEA fuel system cleaners. This, combined with extended oil change intervals (OCIs), led to the low-tension piston rings sticking, which resulted in oil consumption. Many of these engines were severely damaged due to owner neglect, as they were run low on oil.
A rod knock might be invisible, but it's certainly not inaudible. Many owners, whose engines didn't seize from neglect, continued driving their vehicles with knocking sounds until at least one rod exited the block. Subsequently, they blamed Hyundai for the failures.
You might wonder why people treated their cars this way. It's important to consider that Hyundai/KIA's target demographic ten to fifteen years ago consisted of low to medium-income customers, many with sub-prime credit. For me, Hyundais were always affordable vehicles that didn't cost much to own and maintain. I never encountered major issues with them and could always justify my warranty claims, which were few and never drivetrain-related.
Many of these customers were not educated on vehicle maintenance and lacked the financial means to pay for it. Consequently, their Hyundais and KIAs received minimal maintenance, if any.
Additionally, there is a category of buyer I refer to as the "smart wannabe buyer." These individuals purchase used vehicles, thinking they can save on depreciation. The problem is that buying a used Hyundai/KIA often means inheriting the previous owner's neglect. If the vehicle was repossessed, it is almost certain that no one took proper care of it.
I hope this clarifies why Hyundais and KIAs have a perceived reliability issue in the US. If Toyota or Honda had lowered their prices in the past decade and offered financing to anyone with a pulse, they would likely face similar challenges today.
