Tesla’s Model S recommendation was withdrawn by Consumer Reports, which cited reliability issues, but another service claims the car’s dependability has actually improved. TrueDelta.com a private membership-based auto reliability tracking service, claims that the Model S sedan’s reliability has improved by about 20% from last year.

Tesla CEO Blames Early Model S For Low CR Score

Tesla questions CR’s methodology

Raising questions about Consumer Reports‘ methodology, Michael Karesh, who runs the TrueDelta website, said for the survey, Consumer Reports asks owners to report the serious problems they face, and this is the reason it saw a sharp rise in complaints. Karesh said the reliability of the Model S is three to four times better than a typical new vehicle.

Karesh said the likeliness of an owner reporting a problem on the CR survey tends to get lower if a person is enthusiastic about his car or if the dealer provides them with outstanding service. “I think what has shifted is owner expectations, not the number of flaws. The early adopters tend to be very forgiving of glitches. As you expand the consumer base you get people who have less tolerance for problems.” Karesh said that Tesla gets the problems fixed for its customers, and its customer service fetches high marks.

Tesla CEO Elon Musk notes the same thing in his tweet on Wednesday, saying that when it comes to service, Tesla gets the top rating. “Most important, CR says 97% of owners expect their next car to be a Tesla (the acid test).” Questioning Consumer Reports‘ survey, Musk said that it included many of the early production cars, but those issues have been addressed in newer models.

Small sample size

TrueDelta’s analysis is based on the specific problems that have all been fixed. However, the sample size of the survey is small, as it covers about 100 owners. In contrast, Consumer Reports‘ survey had a population size of 1,400 owners.

On Tuesday, Consumer Reports pulled its recommendation for the Model S, saying its reliability is worse than average. It added that several Model S owners reported many issues with the drivetrain, power equipment, charging equipment and giant iPad-like center console. They also reported issues with the vehicle’s body and sunroof squeaks, rattles and leaks.

On Wednesday, Tesla shares closed down 1.38% at $210.09. Year to date, the stock is down by over 5% while in the last three months, it is down by over 25%.