Probably due to the mediocre reviews it got at launch, combined with the game being more of a tech demo for PS4 than anything else.
Racing games have sold well in the US, but it's only the biggest, most recognizable IPs that sell (GT, NFS, Midnight Club, Forza, etc), and many of these franchises have been suffering from "burnout" lately due to so many releases over the years, pardon the pun.
On 2/24/13, MB1025 said:
You know I was always wondering why no one ever used the dollar sign for $ony, but then I realized they have no money so it would be pointless.