It’s not uncommon for automakers to make fixes after receiving bad reviews, says the head of automobile testing at Consumer Reports. What’s groundbreaking is the way Tesla remedied a brake problem by pushing out a software update for its Model 3.

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SAN FRANCISCO — Days after Consumer Reports ripped Tesla’s new Model 3 electric sedan for substandard brake performance, Tesla issued a fix — and Consumer Reports now recommends the car.

Consumer Reports originally recommended against buying the Model 3 in a review published May 23, blaming in large part long stopping distance in brake tests. It retested the car after Tesla provided an over-the-air software fix for all Model 3s and said Wednesday that stopping distance had improved dramatically — by 20 feet.

It’s not uncommon for manufacturers to make fixes after receiving bad reviews, said Jake Fisher, the head of automobile testing at Consumer Reports. What’s groundbreaking, Fisher said, is the way the brake problem was remedied: through Tesla’s over-the-air software update system.

Tesla recalibrated the brakes by remote control, streaming data to Model 3 computers in a manner roughly analogous to the way Spotify streams songs to a smartphone.

“We very often find deficiencies in vehicles,” Fisher said. “What’s unique is how quickly they’re able to react.”

In the May 23 review, Consumer Reports said: “Tesla’s stopping distance of 152 feet from 60 mph was far worse than any contemporary car we’ve tested and about 7 feet longer than the stopping distance of a Ford F-150 full-sized pickup.”

After the update, stopping distance was 132 feet.

To test the brakes, a driver stomps hard on the brake at 60 mph, and the stopping distance is measured. Consumer Reports said it repeated the test several times on two different Model 3 vehicles.

After the software update, stopping distance improved by 20 feet.

Although most automakers offer limited over-the-air services — emergency assistance, for instance — Tesla is the only one that regularly updates major vehicle systems with fixes and new features this way.

“If this were another automaker, there might be recalls, or service bulletins, and owners would have to take their cars in to get them fixed,” Fisher said.

Last week, Fiat Chrysler recalled 4.8 million vehicles to fix a software glitch that could prevent a driver from disengaging cruise control. (The Tesla brake fix was voluntary. Government officials did not raise safety issues or order a recall.)

All automakers are developing similar systems, but unlike Tesla, they must remake “legacy” automobile network systems that reach decades back into the 20th century.

“It’s an uncomfortable position for automakers,” said Mark Wakefield, managing director at consulting firm Alix Partners. Customer privacy and fear of hackers are two big issues. “The risk is that someone can remotely know where you are and, even worse, take some control of the car,” he said. Theoretically, someone could slam on the brakes at the push of a button.”

But when Tesla began offering over-the-air updates, it was a “wake-up call” for the industry, which is now scrambling to catch up, Wakefield said.

There’s plenty of business incentive, not just for safety and cost savings. Over-the-air software will increasingly resemble a smartphone on wheels, with all the revenue generation that implies: selling apps, charging for data, pumping advertising into the car, and likely new paid services no one’s thought of yet.

Timo Littke, business development manager for over-the-air software at Here, a mapping and location company majority owned by Audi, Daimler and BMW, said automakers must balance innovation with safety and privacy. “The smartphone usually won’t put people’s lives in danger, but a car update can do that,” he said.

Tesla’s brake fix illustrates how safety and performance upgrades can be sent directly to a vehicle with no need to visit a dealer or repair shop.

The basic mechanism of disc brakes, like those on the Model 3, is simple: A pair of calipers clamps down on both sides of a spinning metal disc.

But “it’s not just a matter of ultimate clamping force,” Fisher said. With the advent of anti-lock brakes in the 1970s, computer code began playing an increasingly crucial role in brake calibration.

“It’s a matter of how the software determines the maximum force that is used to stop the vehicle but prevent a skid,” Fisher said. “A good system will feel the impending lockup and allow just enough slide so you still maintain control but get maximum stop.”

Dozens of variables are weighed when an automaker sets the base calibration for a car’s brakes. Fisher couldn’t say why Tesla didn’t calibrate the Model 3 to meet the Consumer Reports test requirements from the start. “Depending on how well the software is written, it could make a big impact on the (stopping) distance,” he said.

Tesla declined to make an executive available to discuss the company’s over-the-air update feature.