HarryEaster on 16 January 2008
GT3 had massive bundling in Europe / America and PS2 was bigger than PS worldwide.
PS3 is definitely not bigger than PS2!!
Plus we are talking about Japan, where your argument falls down 
GT (PS) - 2.55
GT2 (PS) - 1.71
GT3 (PS2) - 1.89
GT4 (PS2) - 1.16
GT4 Prologue (PS2) - 0.79
GT5 Prologue (PS3) ~ 0.30
GT5 sales - 750k max
