Let's see if I can do this...there's a lot of detail put into every auto-mobile in the game. Standard cars have only a few thousand polygons compared to the hundreds of thousands that the Premium cars do. I'll assume each Standard car is 3MB, and each Premium car is 15MB on the disc, so there's opportunity for about 750 Premiums in GT6. Question is, is PD going to take advantage of this opportunity to give us that many cars, if I think this is going to go where I think it is? That might depend on the number of songs put into the game.
EDIT: Let's say there's 250 songs in GT6, each one between 8 & 30MB in size. This is assuming that the file format used is 320kbps OGG Vorbis. Assuming the average file size across all the music files is 13.5 MB, you're looking at over 3 GB of music...so that's about 200-250 Premium cars gone to make room for the soundtrack. Or, they could just keep all the Premium cars and still have room for everything else in the game, from UI to tracks to Online content to DLC. On a downer note, installation would take longer...but I just want to play the game and hear what Sony put in here.
EDIT 2: I do not see space as an issue unless you have about 23-24 GB worth of content on there...my problem is, who is going to be able to pay the licensing fees to feature songs in GT6? PD is the company making the game, so I think that they would have to pay all of their licensing fees to Sony. Then again, Sony owns PD so I don't see payment of licensing fees being much of an issue, either.
EDIT 3: This leaves question for how much music that ISN'T licensed by Sony will appear in the game. It'll most likely follow the trend that I think started in GT3 with Daiki Kasho. I think that trend is by default, any music not licensed by Sony is set to not play during races. (I'm sure Sony will find a way to license this somehow...) In before...wobble wobble wobble wobble?
EDIT 4: How does removing music from a video game result in anything more being added to it? It doesn't. I just want to demonstrate how editing a post works.
EDIT 5: (And by the way, here's my real post) Isn't PD obligated to put licensed music from Sony into their games to begin with?