Since GT4 was never officially released for Windows, the primary way to play this version is through the PCSX2 Emulator on a PC or Steam Deck.
: Over a dozen new events and missions, including road rally courses added to road race rotations.
Which of the three would you like?
To download and run Gran Turismo 4 with the best possible visual and performance enhancements, you should PCSX2 emulator paired with the Spec II mod HD Retexture Pack
The Ultimate Guide to Gran Turismo 4: Downloading and Enhancing for HD