The easiest and fastest way is if you have a friend who works there and could schedule an appointment with the tours team. They also host tours for orgs and Tesla owners. 

https://www.quora.com/Is-it-possible-to-get-a-tour-of-the-Tesla-headquarters-or-factory

2.  tesla官网论坛：

You need to send an email to the email address: factorytours@teslamotors.com

Plus you need to be an owner.

https://forums.tesla.com/forum/forums/how-book-fremont-factory-tour?

3.今年5月 Tesla Tour 恢复的新闻：

https://www.mercurynews.com/2019/05/30/tesla-fans-rejoice-as-fremont-plant-tours-return/

4. Tesla Tour视频：

特斯拉工厂最好的介绍，自然非Elon Musk莫属：

5. 你如果对Elon Musk的Tesla感兴趣，这里有更多的介绍：

http://blog.wenxuecity.com/myblog/29065/201412/32395.html