Forza Motorsport 4 spans two disks on the Xbox 360 and the second disk is filled with extra cars to use in the game. The embargo on the game lifted today and we can tell you how much space you'll need on your hard drive for the second disk and how much space the optional install on the first disk will take.
The second Forza Motorsport 4 is called the "install disk" and includes four car packs that takes up 2.8GB of space on the hard drive. The car packs can be installed individually when prompted through the game as you porgress. If you play on multiple Xbox 360s, you'll want to install the second disk on both or the cars will be deleted from your garage thanks to an odd occurence when you try to play on a console without the the second disk installed.
If you choose to install the first Forza 4 disk, it will take up 7.6GB of space which is close to the max size of the new format for Xbox 360 disks. The recently released Gears of War 3 used 7.5GB.
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