It was “a master class in emotional intelligence”, raved the business magazine Inc, and “a powerful lesson in authentic, heartfelt leadership”.

Elon Musk, the chief executive of Tesla, had emailed his entire staff following the May 2017 publications of separate investigations by the Guardian and a workplace safety organization showing high injury rates at the company’s northern California electric car factory.

“No words can express how much I care about your safety and wellbeing,” Musk wrote. “Going forward, I’ve asked that every injury be reported directly to me, without exception. I’m meeting with the safety team every week and would like to meet every injured person as soon as they are well, so that I can understand from them exactly what we need to do to make it better. I will then go down to the production line and perform the same task that they perform.”

Musk, an accountability Houdini, had turned the fact that some of his employees were dealing with life-changing injuries into glowing press about his leadership. If only his promises were true.

“He didn’t meet with me,” said Richard Ortiz, a former Tesla factory worker who was injured at work in July 2017.

“That’s PR; that’s bologna,” said another current Tesla employee, who said Musk had never met with him about the three pinched nerves in his arm.

“He didn’t meet with me, and my incident was filed,” said a third Tesla employee, who was injured in October. “If he was truly going to meet with all the employees who got injured, he would be here for half the year.”

Whether Musk ever intended to follow through on his word to meet “every injured person” is an open question. But in conversations with more than 10 current and former Tesla employees over the past month, workers described the consequences of having a boss whose bombastic promises – to shareholders, to customers and to them – frequently go unfulfilled. While the billionaire’s loose tongue and overly optimistic pronouncements may still excite his legions of fans and customers, many factory workers feel that they have become collateral damage.

Of the workers who spoke to the Guardian for this article, six had been injured at work. None of them ever heard directly from Musk or had him perform their task on the assembly line.

Workers inside the Tesla factory speak of intense deadlines and injuries. Photograph: Joe Skipper/Reuters

A Tesla spokesman said that Musk had met with injured workers “many times” and worked on the assembly line “many times” and provided the names of 10 workers that they said could attest to this. “Elon is in the factory, on the production line, nearly every day,” the spokesman said of Musk, who is also the CEO of two companies, SpaceX and the Boring Company, that are based in southern California. “A significant part of his time is spent talking directly with production employees about what improvements they would like to see or concerns they have.”

“I’ve only been here for five months, and I’ve seen [Musk] four or five times,” said Jimmy Guajardo, who works on the Model 3 and is employed by a subcontracted temp agency. “It felt really good seeing him on the line.”

Of the 10 workers whose names Tesla provided, the Guardian was able to reach four, including Guajardo. None of the four had ever been injured, but they all praised Musk and said they had seen him at the factory.

You have to do it like we do it, 12 hours a day, six days a week … That’s where the wear and tear comes from

Ortiz, an outspoken supporter of a unionization drive at the factory, argued that even if Musk had performed every injured worker’s job, it’s unlikely the experience would have helped the CEO truly understand the challenges and dangers of the work.

“Anyone can do anything for an hour,” Ortiz said. “You have to do it like we do it, 12 hours a day, six days a week … Live the life we live. That’s where the wear and tear comes from.”

Musk’s pledge to meet with every injured worker is by no means the only example of his over-promising. The CEO is notorious for making exaggerated claims about his businesses, whether he was announcing that he had received government approval for a New York to Washington DC hyperloop (he hadn’t), promising to test-drive a fully autonomous Tesla coast-to-coast by the end of 2017 (he didn’t), or claiming that the Model 3 production would reach 5,000 cars per week by the end of 2017 (it still hasn’t).

To one worker, an immigrant who started at Tesla in 2017, the contrast between what Musk promises and what he does is indicative of a lack of “principles”.

“In my country we have a saying, ‘Even if your enemy is a rabbit, you should at least recognize that he has big ears,” he said. “I like Elon Musk … I like people who dream big.”

But, he added, “I’m always really surprised how he keeps giving numbers that we have never been able to respect. He would say we would produce such and such cars by such date, and we are never able to hit it. For me, a responsible person should stick to his word.

“As a Tesla employee, I am really ashamed when my CEO is lying to the public.”

‘I couldn’t believe he said that’

Though Tesla factory employees may have learned to take Musk’s words with a grain of salt, the billionaire’s pronouncements – whether issued by company email, investor earnings call, the press, or Twitter – still loom large over the workplace.

In May 2017, Musk emailed the entire company a message about “doing the right thing” – ie being considerate of minorities and “not being a huge jerk”.

The email resurfaced later that year, as Tesla was hit with a number of lawsuits from employees alleging sexual harassment, gender discrimination, racism and homophobia in the workplace. (Tesla has denied wrongdoing.) One of the lawsuits took particular issue with one line in the Musk email that read: “In fairness, if someone is a jerk to you, but sincerely apologizes, it is important to be thick-skinned and accept that apology.”

Tesla defended the email in a blogpost, arguing that the “counterpoint” to not having a thick skin and accepting an apology “would be a cold world with no forgiveness and no heart”.

Elon Musk on the cover of Rolling Stone magazine in 2017. Photograph: Alicia Canter/The Guardian

But to some Tesla workers, the email was perceived as a green light for harassment and discrimination.

“I couldn’t believe he said that,” said one Tesla worker, who is black and has worked for the company since October 2014. “That’s like he opened the door for his HR and management teams to act accordingly.”

The worker, who asked not to be identified because he fears being fired, said that he feels he is treated like “a dummy” because he is black.

“Things said have made me feel like I was being called a nigger,” he said. “I don’t think people of color should have to have thick skin when it comes to racial issues in the workplace, as Elon’s email suggested.”

Another Tesla factory worker, Branton Phillips, also said that Musk’s “thick skin” line has been adopted as an excuse for bad behavior.

“I would never have my daughter work in there,” the 55-year-old materials handler said. “It’s like a nightclub attitude; it’s wrong. The leads and supervisors that see [harassment], they don’t want to make a big deal. They all say, ‘Have a thick skin … Hey girl, have a thick skin.’”

A third Tesla worker, a US army veteran, concurred that telling people to have a “thick skin” had become the “dismissive philosophy” of Tesla’s management, adding that he had heard workers “outright call people the N-word with little to no repercussions”.

“Tesla is absolutely against any form of discrimination, harassment, or unfair treatment of any kind,” the company spokesman said. The spokesman denied that the email was a signal to anyone not to take harassment seriously.

Racial slurs aren’t the only language that the army veteran objected to. This spring, in two emails to company staff, and on an earnings call with investors, Musk debuted new language to describe a problem weighing down the good-ship Tesla: “barnacles”.

When the big alpha dog of the factory uses that word, it allows others to start thinking about people like that

“The number of … third-party contracting companies that we’re using has really gotten out of control, so we’re going to scrub the barnacles on that front,” he said on the investor call. “We’ve got barnacles on barnacles. So there’s going to be a lot of barnacle removal.”

A Tesla spokesperson said that Musk was referring to contractor companies, not subcontracted employees. But whatever Musk’s intent, the words were interpreted as an insult by some of the hundreds of factory workers Tesla hires through subcontracted staffing agencies.

“When the big alpha dog of the factory uses that word to describe people, it allows other people in the factory to start thinking about people like that and acting that way,” said the veteran, who worked for Tesla through a contracted staffing agency for eight months before being hired directly. He compared the rhetorical tactic to Donald Trump calling certain countries “shitholes” or the US military dehumanizing enemy soldiers with slurs.

“When Elon calls lower-paid workers barnacles, then you have managers saying, ‘Get out of here barnacle,’” he told the Guardian a few days after Musk’s earnings call. “I’ve heard that word more in the last week than in the rest of my life.”

‘The main export is injuries, not cars’

When an engineer with extensive experience in the military and private sector went to work for Tesla in 2016, it didn’t take long for him to start to feel uneasy about his new job as a program manager.

“They were trying to drive home that if you want to go work for a company that will give you enough time to do your job, then this isn’t the place,” the engineer, who has since left the company, said of his orientation. “I came from a background where process was a good thing. At Tesla, the time it took to say the word ‘process’ was too long.”

For the engineer and many of the rank and file factory workers, there was a direct link between Musk’s aggressive production projections and their own working conditions. For some employees, like the engineer, the high stress and long hours interfered with having any kind of family life. For others, however, working at Tesla has left them with life-altering injuries.

“Just that one day at Tesla, holy moly it changed my life,” said Mark Vasquez, 40, of the day in 2015 when he permanently injured his back while working at Tesla. He lost his apartment when he was assigned “light duty” work that paid a significantly lower wage, had to sell many of his belongings to make ends meet, and still deals with pain and numbness in his legs.

“I don’t go out,” he said. “I hardly see my friends. It’s depressing to have them see me like this. I can’t walk for 10 minutes without getting winded and having to stop and sit down … When I have to go to the stores, I have to use one of those electric scooter carts, and I don’t want to do that.”

The Tesla factory in Fremont, California. An investigation found the company had kept injuries off its books. Photograph: Josh Edelson/The Guardian

Another factory worker detailed having two surgeries to address carpal tunnel syndrome and tendinitis in both hands – injuries he attributes to working 12-hour shifts, six days a week, on suspended vehicles with his arms above his head.

“If I were a lazier person, I probably wouldn’t be injured at all,” said the worker, who said he is still in constant pain. While he is still employed by Tesla, he finds the “light duty” tasks that he gets assigned to be humiliating, like “standing in front of the class with a dunce cap”.

But the worker, who is 41 and started at Tesla in 2014, doesn’t see many other options. “The problem is that everything that I know how to do is with my hands,” he said. “Everything that I ever heard of doing is with my hands, and I can’t do it.”

The Tesla spokesman defended the company, saying: “Production will never take precedence over safety – and the numbers demonstrate this. Last year, when production increased 20%, our injury rate declined more than 20%.”

A major investigation by the Center for Investigative Reporting’s Reveal has cast serious doubt over Tesla’s claims about its injury rates, which must be reported to workplace safety regulators. Reveal found that Tesla had kept injuries off its books, making the company’s safety record look better than it was, and the government has opened an investigation.

In recent months, three lawsuits have been filed against Tesla alleging that the company is violating California labor laws by, among other things, failing to provide workers with legally mandated breaks. Tesla said that it “goes above and beyond the requirements of California and federal law in providing all workers with meal and rest breaks and appropriate overtime pay.”

“There have been plenty of times that I had to pick between eating or using the bathroom,” said one employee. “It’s not about time away from work, but time to refuel ourselves and relieve ourselves. No one can work 100% if they really have to go to the bathroom.”

Between the pressure, the long hours, and the difficulty of the work, the factory had become a “perfect storm” for injuries, said Phillips. “There’s not a big safety culture, and they’re pushing the kids super hard for production. It’s just going to be injuries everywhere.”

The army veteran put it another way: “This company is pumping in aluminum, and the main export is injuries, not cars.”

As media scrutiny of the injury rates continues, however, Musk has begun speaking about the issue with his usual lack of restraint.

“We’re well on our way to an injury rate that’s less than half of the auto industry,” he said at the company’s shareholder meeting in June 2017. As Reveal documented in its recent investigation, the company’s overall injury rate for 2017 ended up being slighting above the industry average.

When Tesla shareholders met for their annual meeting this year, Musk played the same card, asserting that the company has “a good shot” at having an injury rate of half the industry average for 2018. During the meeting’s question and answer session, one shareholder asked Musk about his regular failure to meet the timelines he sets.

“This is something I’m trying to get better at,” Musk said. “I’m a fairly optimistic person.”