I've been trying to tell people in othe GT threads how much does this actually mean to the actual GT panorama.
A prologue, which many people called a "glorified demo" (with more content in terms of cars than most NFS games) managed to do 4M+ even if it's factoring the DD and the bundles.
Being that, once GT5 releases, the userbase of the PS3 is going to be almost triple of the userbase when GT5:p released, and almost triple of the userbase of the PS2 when GT3 released (the best GT game so far), this game is going to sell immensily well.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
