Last year, Consumer Reports couldn't get enough of Tesla's Model S all-electric midsize sedan, even calling it "the best car ever tested" and giving it an unbelievably high score of 99 out of 100. However, with 15,743 miles into the test, the no-ads auto review magazine backtracks a bit on its statements after discovering a few "minor" glitches.

Gabe Shenhar, an automotive testing engineer for Consumer Reports, still thinks the Model S' driving performance and safety features are better than most gasoline-powered vehicles, but he predicts that the car's reliability score, which is determined by Consumer Reports subscribers who own a Model S, will most likely go down. He does, however, highlight the fact that his long-term review of the Model S uses only "a sample size of one" and that the "purely anecdotal" reviews by Consumer Reports do not affect a car's reliability score.

"Our car has now been driven at some length by many staff members, many of whom aren't involved in car testing," writes Shenhar. "Car nut or not, EV fan or not, everyone has raved about this car, impressed with its smoothness, effortless glide, and clever, elegant simplicity. In that time, it's also displayed a few quirks-some unique to Tesla."

Shenhar notes Tesla was quick to fix problems with the car's automatic retracting door handles, which sometimes fail to emerge from the car's panel and prevent the driver from opening the door and getting out, by beaming an over-the-air update to the car. He also says that at 12,000 miles, the car's 17-inch center screen, which controls just about each of the car's functions including the controls for opening the car's charging ports, went blank. At 15,700 miles, Shenhar says the car's front trunk lid stopped responding to the controls on the center screen and the chargers' adapters fell apart.

In last year's consumer survey on the Model S, Consumer Reports gave the car's 2012 and 2013 models a reliability score of average based on the answers of 638 owners who responded to the survey. This year, the survey will include consumer reports on the latest Model S 2014.

It is common for advanced vehicles to have their unique share of technical difficulties. Plus, if Consumer Reports had not given the Model S such a high rating in the first place, it might not be paying so much attention to all these problems. Tesla has yet to respond to the latest review of the Model S, but Tesla's firebrand CEO Elon Musk did acknowledge problems at an investors' conference earlier in July.