TeslaCEO Elon Musk to Amazon.Com IncAdvice from Rivian, a Ford-backed electric car start-up: don't run without learning to walk. Take care of your first factory before you rush to build a second factory.

It was reported earlier this week that Rivian would invest at least $5 billion to build its second assembly plant near Fort worth, Texas. The new plant is expected to have an annual capacity of 200000 vehicles and will create at least 7500 jobs by 2027.

The news prompted Mr Musk to comment and suggested that Rivian should first "get its first plant up and running" because mass production at an affordable unit cost is extremely difficult.

Musk is on Twitter.The post said: "I suggest they get the first factory up and running first." It is extremely difficult to achieve mass production at an affordable unit cost. "

Musk later agreed with a netizen's response to his earlier tweet detailing how most of the plant's problems were discovered in the production process rather than in advance. It is unwise to expand production blindly without learning from these mistakes.