Initial quality is measured by the number of problems experienced per 100 vehicles (PP100) during the first 90 days of ownership, with a lower score reflecting higher quality. In this year's study, quality improves across six of the eight categories measured, with 21 of the 31 brands included in the study improving their quality from 2017. The industry average of 93 PP100 is 4 PP100 better than in 2017.

"There's no question that most automakers are doing a great job of listening to consumers and are producing vehicle quality of the highest caliber," said Dave Sargent, Vice President of Global Automotive at J.D. Power. "That said, some vehicle owners are still finding problems. As vehicles become more complex and automated, it is critical that consumers have complete confidence in automakers' ability to deliver fault-free vehicles."

Following are some key findings of the 2018 study:

• Most vehicle areas improve: Of the eight categories measured, vehicle exterior improves the most, now at 15.2 PP100, compared with 16.6 PP100 in 2017. Improvements include less wind noise and fewer paint imperfections. Significant year-over-year improvements also occur in the seats (8.0 PP100 vs. 8.7 PP100) and vehicle interior (14.3 PP100 vs. 14.7 PP100) categories.

• Porsche 911 posts best score of any model: The Porsche 911 has the lowest overall problem level (48 PP100) of any model this year. This is also the lowest level recorded in this generation of the study (2013-2018). The U.S. Initial Quality Study, which was first published in 1987, is currently in its fourth generation.

• All domestic corporations improve faster than the industry: Fiat Chrysler Automobiles (7 PP100 improvement), Ford Motor Company (5 PP100 improvement) and General Motors (5 PP100 improvement) all outpace the industry average rate of improvement (4 PP100).

• Infotainment problems are decreasing: Audio/Communication/Entertainment/Navigation (ACEN) remains the most problematic category for new-vehicle owners. However, this area has improved for the third consecutive year, led by fewer problems with built-in voice recognition systems.

• Globalization of auto industry continues: Vehicles in the 2018 study are manufactured in 25 countries, 11 of which weren't present in the study five years ago. Those 11 countries include Brazil, China, Finland, India, Italy, Netherlands, Poland, Serbia, Spain, Thailand and Turkey. The other 14 countries include Austria, Belgium, Canada, France, Germany, Hungary, Japan, Mexico, Slovakia, South Africa, South Korea, Sweden, United Kingdom and United States.

• Increasing problems with driver assistance systems: As automakers add more advanced driver assistance systems to their vehicles, more consumers are experiencing problems. The level is still low (3.5 PP100 on average) but has been increasing by about 20% a year for the past three years.

"As we look to the future, avoiding problems with safety and driver assistance technology is critical," Sargent said. "In an era of increasingly automated vehicles, vehicle owners have to be comfortable using foundational technologies like lane keep assistance and collision avoidance. Otherwise, automakers will not easily overcome consumer resistance to fully automated (driverless) cars."

Highest-Ranked Brands and Models

Genesis ranks highest in overall initial quality with a score of 68 PP100. Kia (72 PP100) ranks second and Hyundai (74 PP100) ranks third. This is the first time that three Korean brands are at the top of the overall ranking, and it is the fourth consecutive year that Kia is the highest-ranking Mass Market brand. Porsche (79 PP100) ranks fourth and Ford (81 PP100) ranks fifth.

Mazda is the most-improved brand, with owners reporting 25 PP100 fewer problems than in 2017. Other brands with strong improvements include Mitsubishi (20 PP100 improvement), Cadillac (15 PP100 improvement), Infiniti (15 PP100 improvement), Hyundai (14 PP100 improvement) and Lexus (14 PP100 improvement).

The parent company receiving the most model-level awards for its various brands is Ford Motor Company (five awards), followed by Hyundai Motor Group (four), and BMW, General Motors and Nissan (three each).

• Ford Motor Company models that rank highest in their respective segments are Ford Expedition; Ford Mustang; Ford Super Duty; Lincoln Continental; and Lincoln MKC.

• Hyundai Motor Group models that rank highest in their segments are Genesis G90; Hyundai Tucson; Kia Rio; and Kia Sorento.

• General Motors models that rank highest in their segments are Buick Envision; Chevrolet Silverado; and Chevrolet Silverado HD.

• BMW models that rank highest in their segments are BMW 4 Series; BMW X1; and BMW X6.

• Nissan models that rank highest in their segments are Nissan Altima; Nissan Frontier; and Nissan Maxima.

Other models that rank highest in their respective segments are Acura ILX, Dodge Grand Caravan, Mercedes-Benz GLA and Toyota Corolla.

Plant Quality Awards

Toyota Motor Corp.'s Yoshiwara plant (Japan), which produces the Lexus LX and Toyota Land Cruiser, receives the Platinum Plant Quality Award for producing models with the fewest defects or malfunctions. Plant quality awards are based solely on defects and malfunctions and exclude design-related problems.

Toyota Motor Corp.'s Cambridge North (Canada) plant, which produces the Toyota Corolla, and Georgetown 3 (Ky.) plant, which produces the Lexus ES, each receive the Gold Plant Quality Award in a tie for the Americas region. BMW Group's Dingolfing 02 (Germany) plant, which produces the BMW 6 Series and BMW 7 Series, receives the Gold Plant Quality Award for the Europe/Africa region.

The 2018 U.S. Initial Quality Study is based on responses from 75,712 purchasers and lessees of new 2018 model-year vehicles who were surveyed after 90 days of ownership. The study is based on a 233-question battery organized into eight vehicle categories designed to provide manufacturers with information to facilitate the identification of problems and drive product improvement. The study was fielded from February through May 2018.