Sony announced that Gran Turismo 5 has already sold over 5.5 million copies worldwide in only twelve days after release. This marks over 60 million sales worldwide of the Gran Turismo franchise overall, which is a whole twelve years and eleven months old.

Considering worldwide sales of GT3 are 14.80 million and GT4 are 10.86 million, Gran Turismo 5 is on track to surpass both in sales.  Some people may say the Gran Turismo franchise is irrelevant now, but money talks, and the sales say otherwise.  Personally, I'm not a fan of simulation racers, but I can definitely see the appeal.  Gran Turismo 5 is available now exclusively for the Playstation 3.