What data do we have on sales trends for civ5? And how do they compare to the similar data for civ4 before expansion packs were produced?
No data. Firaxis/2K Games hasn't released that data to my knowledge. I'm sure they'll put their special spin on the numbers anyway when they do.
Just my personal opinion. Like I said, we'll see in a few years.
EDIT:
From Apolyton:
rom VGChartz.com, a good source, Through September 25th (no new numbers available yet):
PC Sid Meier's Civilization V 192,874
This ranked Civ V 6th for the week it was released. These are worldwide numbers.
http://apolyton.net/showthread.php/193279-Civilization-V-tops-PC-chart
Thread on 2K Games talking about the sales figures:
http://forums.2kgames.com/forums/showthread.php?p=1217013
260,000 copies sold by October 2nd. People are not sure if this includes digital downloads or not.
http://www.vgchartz.com/weekly.php