Polyphony has announced that the US and Japanese versions of Gran Turismo 4 have gone gold, with all final bug testing ironed out. The final versions will be sent to production facilities ready for printing within days according to Polyphony head Kazunori Yamauchi.

He went on to make some of the most detailed comments to date concerning the mysterious Gran Turismo Mobile for PSP, about which little aside from a few screens shots has been seen.

“The PSP Gran Turismo will be a little smaller in comparison with the Gran Turismo 4, but it won't be any different from the Gran Turismo series that everyone knows. I think that the key trait of the PSP is that it can be carried around and used for communication. Communication between players and consoles will probably be one of the key aspects of the console and the game.”

For reference, GT4 hits Japan on December 4th and the US on the 14th in the same month. PAL copies are expected on 23rd February 2005.