The Tesla Model S has been highly rated, but there are a growing number of reports about nagging quality issues with the battery sedan.

It has been proclaimed Car of the Year, other critics ranking it among the best vehicles they’ve ever driven. But a small but growing list of critics is now raising concerns about the quality of the Tesla Model S.

That list includes influential Consumer Reports, which complains the magazine’s long-term test vehicle has had “more than its share of problems” – some of which echo the complaints of a Wisconsin doctor who recently won a legal battle with Tesla which ultimately purchased the vehicle back under the state’s lemon law.

When first reviewing the Model S in May 2013, Consumer Reports gave it a score of 99 out of a possible 100, tying the best car the magazine had ever reviewed. But after a year of testing, and of listening to feedback from 637 owners, concerns are beginning to mount, CR reporting, “Given the number of bits and pieces Tesla has replaced on our car, it might be tempting to guess that its reliability score will go down.”

“The reality is, it might,” the non-profit magazine continued, “depending on the frequency and severity of problems reported by our subscribers and whether they show that reliability is below average.”

CR’s Model S experienced a number of annoying issues. The huge video screen on the center of the dashboard used to control virtually all vehicle functions went blank after about 12,000 miles of driving. The trunk latch malfunctioned, and there was a roof creak.

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Another troubling issue involved the car’s flush-mounted door handles, which are supposed to pop out when the driver approaches or touches them. That didn’t always happen, which meant no one could open the doors.

One of the positive things about the Model S design is that Tesla can update software on the fly using over-the-air updates, something that took care of the door problem, while CR’s service team solved the problem with the video screen.

Nonetheless, CR says that, for now, the Tesla Model S has “decent reliability.”

But it’s not the only one to express concerns with the well-equipped sedan it bought in January 2013 for $89,650. Automotive data and pricing site Edmunds.com recently reported issues of its own with a long-term test of the Model S.

Last month, the California-based battery-carmaker agreed to buy back a loaded Model S from Wisconsin physician Robert Montgomery after he complained about a series of unresolved issues, including those pesky door handles and a transmission that wouldn’t always shift into Drive.

The automaker initially resisted, issuing a tart statement questioning the veracity of the claims by Dr. Montgomery and his attorney, the self-styled “Lemon Law King,” Vince Megna. Tesla eventually agreed to a settlement of just over $100,000.

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Tesla has been flying high over the past year despite some setbacks, including a series of battery fires that prompted it to develop a new titanium cage to prevent damage from road debris.

The maker has boasted about its quality efforts, though during a conference call following the release of its earnings last month, Founder and CEO Elon Musk acknowledged, “We definitely had some quality issues in the beginning,” as Tesla got production going. He insisted later vehicles have been doing much better.  The carmaker’s goal, he added, is “to get the car ultimately to the platonic ideal of the perfect car.”

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Musk noted that not only is Tesla able to fix some software issues with over-the-air patches, but it also is adding new features to the Model S.

A real test for the upstart maker comes in the months ahead as it gets production underway with its second vehicle line, the Model X sport-ute. Industry experts say it is relatively easy to focus on quality when a manufacturer is producing just a single product line. The more models that roll down the assembly line, the more complex and difficult it becomes.