Across all brands, the reliability of 3-year-old vehicles improved 4 percent from last year, Power said. Overall, 13 brands showed improvement while 17 brands, including Porsche and Buick, had more reported problems. Hyundai's results were flat with 2018 but still above the industry average.
The continued rollout of new technology, often embraced first by luxury brands, remains a challenge across the industry.
"Vehicles are more reliable than ever, but automakers are wrestling with problems such as voice recognition, transmission shifts and battery failures," Dave Sargent, head of Power's global automotive practice, said in a statement.
The growing complaints with transmissions coincides with the introduction of 8, 9 and 10-speed transmissions that require automakers to map powertrain software to maximize fuel economy during testing cycles.
"This generally leads to the transmission being in too high a gear or constantly 'hunting' for a better gear," Sargent said in an email. "Consumers like the fuel economy but hate the impact on drivability and smoothness."
Sargent said problems with advanced driver-assist systems such as collision avoidance, park assist, and lane departure warning are also starting to pop up in the survey.
Other top complaints, according to the survey, include built-in Bluetooth connectivity glitches, excessive wind and road noise, navigation systems that are difficult to operate, materials that scuff or soil too easily, inaccurate navigation systems and defective audio systems.
Chrysler, which placed last in 2018, was the most-improved brand, with a decline of 65 problems per 100 vehicles. Other brands with big improvements were Mini, Volkswagen, Jeep, Cadillac, Toyota, Audi and Mitsubishi.
Brands that fell behind with substantially more problems were Fiat, Land Rover, Volvo, Acura, Dodge, Mazda and Lincoln.
The study measures 177 problems grouped into eight major categories per 100 vehicles over the previous 12 months. Original owners of 3-year-old 2016 cars and light trucks were surveyed for the 2019 study.
- Vehicle reliability continues to improve but at a slower pace. The industry average for 2019 was 136 problems per 100 vehicles, an improvement of six problems per 100 cars and light trucks from 2018. That's a lower rate of improvement than the 14 problems per 100 vehicles in 2018 compared with 2017.
- Audi, BMW, Mercedes-Benz and Volkswagen all improved this year and, with Porsche included, the German brands fared better than the industry average for the first time in 30 years of the study.
- The Porsche 911 is the highest-ranked model in the 2019 study.