No Ferraris in it?
Ferrari rights were sold out a long time ago. Microsoft owns most of them (particularly Turn 10, the developer of Forza) for Xbox 360 and PC (and yet they still won't bring Forza to PC *sigh*). Besides them Sony owns most of the rights for PS3. TDU2 also has Ferrari's but that's probably because of an agreement between Atari, Sony and Microsoft. You probably know that the 458 Italia only appears on the PC version of TDU2, because Microsoft and Sony kept it for their own games on their consoles.
Any other post 2002 game that has Ferrari's probably uses them with permission from Microsoft.
EA on the other hand owns exclusive rights for Porsches, unlimited, and for every platform. That's why you will never see them in any other game except NFS and Shift (unless EA decides to make another racing franchise that uses licensed sports cars).
Microsoft tried striking a deal with EA. If you remember Forza 3 had Porsches, quite a lot of them, and about the same time Forza 3 came out EA released a Ferrari DLC for NFS Shift, exclusive to Xbox 360. EA exchanged Porsche rights for Ferrari rights with Microsoft.
They decided not to allow Turn 10 to use Porsches in Forza 4 however (pwned faggots), probably because
I think EA made the right decision, I just wish they would use more Porsches since they own exclusive rights to them...
Pretty much every non-NFS racing game uses ether RUF's or Gemballas to compensate for Porsches, though Gemballa closed down so RUF's remain the best choice...