Auto production lines usually produce about a car a minute. 500,000 cars a year is about two production lines running two shifts. In 2005, the NUMMI plant, which is where Tesla is now, produced 400,000 cars with 4,700 employees. Tesla is talking about reaching 9,300 employees. They do more than final assembly there, but still, that's a high headcount for an auto plant. Ford's Kentucky truck plant also produces about 400,000 units a year with about 4,500 employees.
[1] http://www.autonews.com/article/20160504/OEM02/160509943/2-t...