J.D. Power studies serve as an industry benchmark, and its results can drive sales and impact insurance premiums for owners. The 2021 U.S. Vehicle Dependability Study analyzed responses from 33,251 verified owners of 2018 model-year vehicles sold in the U.S. The study assessed around 150 different models including cars, trucks and SUVs.
Tesla's ranking in the 32-year-old annual study this year is considered unofficial, said Dave Sargent, J.D. Power's vice president of automotive quality. That's because Elon Musk's electric vehicle venture doesn't grant J.D. Power permission to survey its owners in 15 states that require this.
One of the excluded states is California, Tesla's home base and a massive market for the company. However, the J.D. Power study included 756 Tesla respondents from 35 different states including major markets with comparably warm weather like Florida and Texas.
While Tesla rated unofficially low on the dependability survey, it unofficially topped J.D. Power's 2020 APEAL survey, which rates vehicle brands by owners' emotional attachment and level of excitement with their new vehicles.
The dependability survey asks drivers how many and what kind of problems their cars, trucks or SUVs experienced in the past year and assigns a score based on problems reported per 100 vehicles. The lower the score, the more dependable the automaker.
The greatest number of problems reported by vehicle owners across all makes and models concerned audio, communication, entertainment and navigation systems.
"With smartphone apps increasingly giving owners an alternative, some will give up on the vehicle's built-in systems that caused that initial frustration. That's problematic for automakers, as a lot of the vehicle's value is tied up in these systems and they don't want to hand this business over to third parties," said Sargent.
The Porsche 911 was the highest-ranked model in the 2021 study.
Toyota-owned Lexus topped the list among all brands, with a score of 81 problems per 100 vehicles.
Kia vehicles have notably risen from among the least dependable auto brands in the U.S. to most dependable in just a decade, with 97 problems per 100 vehicles on average. Toyota was near the top of the list with 98 problems per 100 vehicles.
Volkswagen, which introduced two new models in 2018, slid in the dependability rankings. Sargent noted: "Results can be affected by whether a manufacturer has just launched a bunch of new products. They tend to be the most problematic their first year out."
Owners of 3-year-old Teslas reported 176 problems per 100 vehicles, compared with the industry average in the U.S. of 121 problems per 100 vehicles. Tesla owners reported more problems with their exterior and interior than with other systems like propulsion, battery or infotainment and navigation. However, some did complain about troubles with Tesla's in-vehicle voice recognition.
Overall, vehicle dependability improved by about 10% year over year, J.D. Power found. Part of this was due to lower use and abuse of vehicles amid a Covid pandemic that has restricted commuting and travel in 2020 stateside.
"We know the more people use a vehicle the more problems they're going to have," Sargent said. Last year, on average consumers had driven about 32,000 miles over three years of new vehicle ownership. This year, they had driven 29,000 miles -- representing a 10% reduction over a three-year period, and an implied 30% reduction in the last year.
-- CNBC's Michael Wayland contributed to this report.