Tesla Motors CEO Elon Musk unveiling large utility scale home batteries at the Tesla Design Studio in Hawthorne, California. Image Credit: AFP

Tesla Inc.'s chief executive officer Elon Musk said he was signing off Twitter for a few days — shortly after tweeting that the $20 million penalty he was given for announcing on Twitter that he had funding to take the electric vehicle maker private was "worth it". 

His sign-off culminated a series of tweets that included an announcement about the release of autopilot drive on navigation.

Earlier this month, a US judge approved Tesla and Musk's $40 million settlement with the Securities and Exchange Commission (SEC) over a probe of Musk's August tweet citing funding being "secured" to take the company private.

Musk would pay a penalty of $20 million as part of the deal.

The SEC settlement required that Tesla implement mandatory procedures and controls to oversee all of Elon Musk's communications regarding the company in any format, including Twitter.

It said any such written communications that contain information material to the company or its shareholders would need to be pre-approved.

Musk took to the social media service Friday, saying "on Twitter, likes are rare & criticism is brutal. So hardcore. It's great." It's drawn more than 105,000 likes, 33,000 shares and nearly 3,000 comments.

A Twitter user wrote to him asking: "How about the one that cost you 20M, how was the 'like' ratio on that one?".

Musk responded to the tweet with "worth it."  

A notorious workaholic, Musk doesn't spend cash on lavish vacations or expensive hobbies. Business Insider reported on August 24 that Musk was then worth about $23 billion and has never taken a paycheck from Tesla. 

The father of 5 spends has never taken a paycheck from Tesla, refusing his $56,000 minimum salary every year.

In January, Tesla announced it would pay Musk "nothing" for the next 10 years — no salary, bonus, or stock — until the company reaches a $100 billion market cap. 

Tesla under US criminal probe for Model 3 comments: source

Meanwhile, US criminal investigators are probing whether Tesla Motors misled investors about the timetable for meeting key car production targets, a person familiar with the matter said Friday.

The investigation was the yet another tangle with federal authorities for the electric automaker, whose share price was repeatedly buffeted earlier this year after a series of erratic-seeming comments by Musk.

The probe, which has been underway since earlier this year, concerns whether the automaker told investors it was on track with targets for the closely-watched build-out of the Model 3 car despite knowing it could not meet such goals, The Wall Street Journal reported Friday.

A Tesla spokesperson confirmed the company had received a "voluntary request" earlier this year from the US Department of Justice about its "public guidance for the Model 3 ramp" and cooperated with the request.

"We have not received a subpoena, a request for testimony or any other formal process, and there have been no additional document requests about this from the Department of Justice for months," the Tesla spokesperson added.

The Justice Department has also been probing Musk's statements about taking the company private.

The Wall Street Journal described the Justice Department's probe of the Model 3 as "deepening," saying the Federal Bureau of Investigation in recent weeks had sought to interview a number of former Tesla employees who had been subpoenaed earlier.

The Tesla spokesperson said the company had been "transparent" about "how difficult it would be" to meet targets.

"Ultimately, given difficulties that we did not foresee in this first-of-its-kind production ramp, it took us six months longer than we expected to meet our 5,000 unit per week guidance," the spokesperson said.

"Tesla's philosophy has always been to set truthful targets — not sandbagged targets that we would definitely exceed and not unrealistic targets that we could never meet."

In August, a federal judge in California dismissed a case brought by investors who had sued over Tesla's statements about the Model 3.

The company on Wednesday reported an "historic" profitable quarter driven by demand for the mass-market Model 3.

Shares closed up more than five percent on in New York on Friday, adding to Thursday's gains.