The issue here is that Gran Turismo caters more towards car enthusiasts than hardcore gamers, I'd wager.
It's kinda like Madden. In the US, everybody knows a guy that only plays Madden. I know a couple of people that are the exact same way with Gran Turismo, and I'm sure in Europe you'll find something similar, if not far more prevalent.
Many of these people are also the type of people that'll pick up a console later in its lifecycle, which leads to long legs for something like GT. Kinda like how Madden was still selling millions on ps2 as late as 2008.








