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Tesla’s Model S sedan scored an unprecedented “99 out of 100” from Consumer Reports last year, but the glowing endorsement from this influential publication could turn out to be short lived. Sources indicate the reliability of this car may have taken a slide.

It’s no secret the Tesla Model S is a fine car. This all-electric luxury sedan accelerates with the force of a tsunami, it’s loaded with the latest technology including a massive high-resolution display and it even delivers a lively driving experience. For a new brand that by automotive standards is in its infancy, this vehicle is nothing short of miraculous.

We’re not alone in singing the praises of Elon Musk’s pride and joy. Consumer Reports is smitten with the Model S as well. Jake Fisher, director of auto testing at the watchdog organization said that on a 100-point scale “we gave it a 99 and subscribers gave it a 99,” noting “we’ve never seen that before.” They praised the car’s efficiency, luggage capacity, assembly quality and more.

This Tesla even drove away with a coveted “Recommended” rating from Consumer Reports. For a vehicle to earn this accolade it must meet a few criteria; it has to perform well in all of their road tests, it’s got to deliver adequate or better crash-test scores and have at least average predicted reliability. Of course the Model S met all of these requirements with a projected dependability score of “average” for 2012 and 2013 models.

IS QUALITY FALLING?

But there could be trouble on the horizon. For 2012, its first year on the market, the Model S earned Consumer Reports’ highest score: a big red dot. However, that figure dropped to below average in 2013 with owners reporting more problems. However, its overall predicted reliability — a combined score from the 2012 and 2013 model years — is average.

“Typically cars do get better with subsequent model years,” Fisher said. When a new vehicle is introduced it generally has the most problems in its first year, then as time goes on the automaker sorts out various issues and quality improves. The situation with Tesla’s Model S is unusual, but he also said “it’s not completely out of the ordinary.”

Consumer Reports isn’t the only game in town that’s identified potential issues with the Model S. Michael Karesh, founder of TrueDelta.com, a site highlighting owner-supplied reliability and fuel economy information said “essentially we’ve been seeing really high repair frequencies.” According to his data, the Model S requires three times as much service as the typical vehicle in his survey. He said on average, a pool of 100 cars will require a total of about 100 repair trips per year; that works out to about one annual service call per Model S.

Admittedly Karesh’s sample size is small; TrueDelta only has about 30 reliability responses for the Tesla Model S (covering both 2012 and ’13 models). He noted that the strength of Consumer Reports is the massive consumer network they leverage. Last year they had more than eight million subscribers and received responses on some 1.1 million vehicles. By comparison, on an annual basis TrueDelta gets about 35,000 respondents.

Interestingly Karesh’s findings mirror what Consumer Reports has noted about this vehicle. The main issues that have popped up in TrueDelta’s survey include rattles, wind noise from the car’s available moonroof as well as a clicking sound in the steering system, all admittedly minor bugs. Consumer Reports gave the 2013 Model S black marks in the “Body Hardware” and “Squeaks & Rattles” categories of its survey.

SEE ALSO: 2013 Tesla Model S Review

Fisher said they’ve also noted some issues with the car’s electrically operated exterior door handles. But in the same breath he said the Model S’s battery, motor and overall drivetrain – major components – have been absolutely flawless.

HOW YOU ASK IS AS IMPORTANT AS WHAT YOU ASK

But just because their findings are similar doesn’t mean they got there in the same way. The methodology employed by TrueDelta and Consumer Reports is dissimilar.

Karesh said “the main difference in my survey, first of all I have people report every repair, not just the ones that are ‘serious.’” Consumer Reports asks respondents to identify problems they consider significant because of factors including cost, safety concerns or vehicle downtime. Participants are asked to include problems covered by warranty but not issues that are the result of recalls or collision damage.

“Any owner biases make their way into the data if you let each respondent decide what should count as a ‘serious’ repair,” Karesh said. Additionally he said that if someone doesn’t like their car they might think an uncomfortable seat is a serious issue; likewise a transmission overhaul might not be considered a serious repair if the owner loves their vehicle or if the dealer took really good care of them.

Despite its question that focuses on “serious” issues Consumer Reports tries to steer clear of those abovementioned issues. Fisher said “we’re very specific about not asking people if they like the car… It’s really about things gone wrong, things that broke.”

Backing this up Fisher said they re-contacted thousands and thousands of people driving vehicles equipped with MyFord Touch in order to verify they were having real problems with the infotainment system, not just gripes about its functionality. He said “we verified this many different ways.”

Another distinction between these two surveys is time. According to Karesh TrueDelta is “much more up to date” because they do surveys every quarter, not annually like Consumer Reports.

Of course Fisher is well aware of the limitations of a yearly study. “We’re definitely looking at doing it more often and becoming more current” he said.

Despite the differences Karesh is not at odds with his larger competitor. Regarding Consumer Reports he said “I put faith in it,” adding “I think most of the time it’s accurate.”

IN THE BLACK OR SEEING RED?

But the real question is why has the Model S fallen from a solid red dot to half a black dot in just one model year? Overall its reliability score is average but trending downward.

Speculating about this Fisher commented on the company’s gradual roll out of the car. He said it’s feasible that “the first vehicles were really given the white-glove treatment [but] as they ramped up production it’s possible some problems crept in.”

Shanna Hendriks, communications manager at Tesla Motors, said they’re “very concerned about quality,” which is why they decided to increase production incrementally. Back in June of 2012 when the Model S was introduced they were only building five per week. Then they gradually stepped up to 10, 20 and 100. “Now we’re at about 600 cars per week” she said and they’re shooting to sell 35,000 of them this year.

Another possible reason for its stellar initial quality scores has to do with the customers that bought them.

“Early adopters might be less inclined to consider problems serious,” Karesh said. He went on to say these people may be more accepting of teething issues that come with an all-new car from a brand-new company.

GOING FORWARD

Automotive quality is likely the best it’s ever been but will the Model S still be recommended once Consumer Reports’ new survey results come out? “It’s hard to say” noted Fisher since they haven’t been published yet but “if it falls below average we will no longer recommend it,” 99-point score or not.

Karesh said the 2014 models could be significantly better, but they’re not really showing up in his survey at this time. Still, he said “I think it’s likely to [lose its ‘Recommended’ rating].”

“Consumer Reports is important to us” Hendriks said, adding that Tesla takes all feedback very seriously. When it comes to quality they have a few advantages other automakers don’t.

“We’re really fortunate that we make a lot of the parts for the vehicle here at our manufacturing plant in [Fremont] California” she said. That allows Tesla to closely monitor quality and make changes more quickly than they could if they relied more heavily on third-party suppliers.

Assuaging potential concerns, the Tesla Model S is backed up by a pretty generous guarantee. The car features a four-year, 50,000-mile new-vehicle warranty while the battery is protected for eight years and either 125,000 or unlimited miles depending on its size (the smaller 60 kWh pack is the one that’s covered for 125,000 miles).

Reinforcing the company’s customer-focused mind-set Karesh noted that Tesla’s service rating is outstanding and he shared an interesting repair-related story that came out of his survey. One owner brought their Model S back to the dealer because a motor in the power seat wasn’t functioning. As it turned out nothing wasn’t actually broken, the connecter was simply unplugged. But to ensure they could promptly correct this issue without inconveniencing the customer, the service department ordered an entirely new seat assembly so they could drop it in if necessary. That’s almost unheard of in the car business and it clearly demonstrates Tesla’s desire to take care of its customers.

GALLERY: 2013 Tesla Model S

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