The letter came just days after Tesla overtook Ford as the most valuable US car company, when it market value hit almost $49bn, compared with Ford’s $45bn.

This was despite Ford delivering 6.6m cars last year, compared with Tesla’s 76,000. Hopes that Tesla's electric vehicles will dominate future transport have since seen the shares climb as high as $312 since then, pushing the company's value to beyond $50bn.

However, Mr Musk - who owns about a fifth of Tesla's shares - took exception at the letter from investors, tweeting in reply to a news report that “This investor group should buy Ford stock. Their governance is amazing …”

He added: “Besides, I already said we'd add more independent members during [Solar City] merger. Will announce soon, but this group has nothing to do with it.”