The only thing I see here that is pretty much out of the realm of possibility is Porsche, if they've gone this long without getting Porsche, its unlikely to happen in the months before release. Everything else is completely reasonable.

I am especially inclined to beleive the part about limiting the amount of cars importable from GTPSP, because if you import a top level car and use it in career mode, it will be no challenge at all. And theres no reason to make them importable for Arcade mode, because all cars are available in Arcade mode.

It's only been 2 months since the announced Bugatti and Lamborghini will be in it so I think there might still be a possibility.

Well that was when they were announced, they could have had the deal for plenty of time in advance. If they had already had Porsche it would have made it into GTPSP. If they got Porsche AFTER GTPSP came out then they would have to add at least 10-30 cars from Porsches stable to accurately represent them, who knows how long that will take.

There is a reason it was delayed, stop being negative

Maybe they want to keep it a secret [if true, which I hope] and besides there is only 2 Lamborghinis in GTPSP.

Well I hope you're right, I'd like to see Porsche in the game (even though I don't particularly like them), it would just be nice to see almost every car manufacturer on board. It would make it definitive so to speak.

I've waited for Porsche since GT1

Aww man, I didn't know Porsche wasn't in the previous games. =( Come on PD, get Porsche!

I never liked Gran Turismo because of pure PS2/PS1 hate, but I'm going to give this one a chance.