The quality of the typical new car has significantly improved over the past decade, but those gains unexpectedly stalled this past year, according to the latest annual survey.

The 2019 Initial Quality Study, conducted by research group J.D. Power and Associates, found that while manufacturers have been resolving some of the nagging problems with high-tech infotainment systems, traditional mechanical problems that had largely faded over the past decade have returned.

“Some traditional problems crept up this year, including paint imperfections, brake and suspension noises, engines not starting and the ‘check engine’ light coming on early in the ownership experience,” said Dave Sargent, the head of automotive research for J.D. Power.

Those problems come as a surprise because manufacturers made a major push over the past decade to largely banish mechanical problems. Once commonplace issues, such as balky transmissions and faltering engines, had become more the exception than the norm.

Sargent also noted that many consumers are reporting problems with the latest wave of advanced driver assistance systems, such as forward collision warning, automatic emergency braking and blind spot detection. That’s a potentially serious issue as ADAS technology becomes the new standard. And these systems are the precursors of the technology that will be needed in the fully driverless vehicles expected to come to the market over the next decade, raising questions about how well they will work.

Power’s study focuses specifically on the issues that owners report with their vehicles during the first 90 days of ownership. And while long-term reliability is examined in a separate study, the Initial Quality Study has traditionally offered insight into which brands will hold up best.

Manufacturers and car buyers alike tend to closely follow the study which, in its early years, helped identify the rise of brands such as Toyota, Nissan and Honda. But there has been a significant shift in the results since early in the decade. Traditionally dominant Japanese marques have begun to lose momentum. At the same time, the South Korean brands once considered quality laggards have made a push to address their early issues, surging to the top of the IQS charts.

Genesis, the luxury brand recently spun off by Hyundai, led this year’s study, with an average of 63 reported problems per 100 vehicles — 63 PP100 in Power lingo. Kia followed with 70 problems per 100, and Hyundai itself had an average 71 PP100.

The best the Japanese could muster was Nissan’s 86 problems per 100 vehicles, putting it in seventh place. Lexus and Toyota came in ninth and tenth, respectively, with their 90 PP100 score barely beating out the industry average of 93 problems. Mazda, Honda, Acura and Subaru, among the other Japanese brands, came in below average.

European brands also suffered some problems in this year’s IQS, with not a single marque exceeding the industry average — though Porsche’s iconic 911 sports car did repeat for the second year as the single, highest-quality product in the industry, with just 58 problems per 100 vehicles. Jaguar was the lowest-ranked brand in the industry, with a total of 130 PP100, while its sibling British marque, Land Rover, fared only slightly better, with 123 PP100.

Ford and its high-line Lincoln division came in just behind the three South Korean brands. That reflects a significant turnaround for Ford, in particular. Earlier in the decade, it had plunged in the IQS results due to both transmission problems and issues with its high-tech Sync infotainment system. And Dodge, another traditional quality laggard, came in eighth this year, ahead of both Lexus and Toyota.

Even some brands that fared poorly overall did have a few good turns in the 2019 IQS. BMW and Mini had three individual models that topped their individual segments: the BMW 2-Series and X4 crossover, as well as the Mini Cooper. But the Hyundai Motor Group, which includes Genesis and Kia, as well as Hyundai, had six individual segment winners, more than any other manufacturer.