It was such a unique experience back then. Nothing like it. Starting with a beat up, used car and slowly but surely making it into the big leagues. It felt great, like a Car-RPG of some sort.
I'm also glad I managed to play the Japanese import version first. I despised all of the musical changes made to the international versions, with their licensed music and the electronic tracks used for the menus. The fusion jazz in the Japanese version helped in providing a more unique, kinda classy atmosphere, especially the tracks composed by T-Square's Masahiro Andoh. Thankfully at least several of the menu themes survived past GT1 for future editions of the franchise.
And of course Moon Over The Castle is the GOAT.