I just started a new game to have a closer look, and I stand by what I said.
New game as Drengi, population 10, +5 manufacturing from Civ capital, yet 100% manufacturing results in 19.4 production.
Edit: Took a screenshot.
http://i.imgur.com/czW71UQ.jpg
I've also noticed that the bonus of "+5 Total Production" from the Civ Capital applies to Manufacturing, Research, and Wealth, however it uses the Manufacturing icon - This can be a little misleading. I didn't realise there was a difference between Production and Manufacturing until now.