How much discount do AIs get to upgrade units?

[alpha wolf 64]

Recently was fighting a multi front war. My damaged GWI were facing healthy rifleman, and my artillery was a few turns behind. So i check the AI economy (0 gold and negative per turn) so I figured that I could afford to wait a few turns. When I launched the attack a few turns later, all theose rifles were now GWI. with no resources left for trade, i doubt that they sold any for cash, so were did they get the money to upgrade?

 

[Smokeybear]

Recently was fighting a multi front war. My damaged GWI were facing healthy rifleman, and my artillery was a few turns behind. So i check the AI economy (0 gold and negative per turn) so I figured that I could afford to wait a few turns. When I launched the attack a few turns later, all theose rifles were now GWI. with no resources left for trade, i doubt that they sold any for cash, so were did they get the money to upgrade?

They pulled it out of their ***. AI does that a whole lot. Supposedly it's to make them competitive with the human player, but in cases like you pointed out, it certainly is fricking annoying.

 

[Jaybe]

According to the CIV5HandicapsInfo.xml, the AI get a 50% discount at (virtually?) all levels. The displays of their treasury & GPT includes adjustments for what they are willing to trade with you.

Whether they can actually convert science/production/culture to gold to provide upgrades, ... I do not know. Perhaps they are bullying CS?