"27.5 million copies sold worldwide." Vgchartz largely undertracked the game, Rockstar confirmed that it's sold 27.5 million copies and that's before factoring in the digital sales. So comparing MW3 with it, I think they're evenly matched at the moment, but CoD will surpass it, and that's just a fact.
However with the decline shown by Black Ops II and the increase in hype for GTA V over GTA IV, I think GTA V will outsell it easily. Problem with GTA IV was that they released the game on the HD twins with minimal install bases, which was like 40M or some shit. When most people finally bought the HD twins they simply bought the game used over new to save money(like I did.) I think the fact that the HD twins now have an install base rivaling the PS2's that this game will sell around 30 Million copies or more between the two.







