This was announced directly by Tesla's CEO, Elon Musk, recently in a TED Talk presentation. Similarly, as quoted from BGR.
Musk said the company wants to build at least four giant mills around the world. "I want to announce a factory between two and four giant mills later this year, maybe four," Musk said on stage.
Currently it has not been decided exactly about the location of the factory in question Musk. It is believed that Tesla is now looking at other locations in the United States, Europe and China.
Previously, Tesla indeed stated that it is actively exploring the possibility of opening a factory in Shanghai, Tiongkok.
"Tesla is very committed to the Chinese market and we continue to observe (possibly opening) manufacturing locations worldwide to meet the needs of the local market," said one unnamed company spokesman.
He added, "We think Tesla's main production car will continue in the United States and we want to continue building local factories to ensure product availability for the markets we serve."
For Tesla, China is certainly a potential target market. In a report, Bloomberg called the construction of a local factory in the country with the largest population, it is expected Tesla can save import tariffs by 25 percent which makes sedan Tesla Model S and Model X more expensive than in the United States.
