Gran Turismo 5 will only need 256 megs to run, but creator Kazunori Yamauchi recommends that users install a bit more than that (via Adriasang).
Responding to a fan’s question over Twitter, Yamauchi recommended a 10 gigabyte installation for the best possible experience. No further details, but we know now that the mandatory installation won’t be a very large one.
Gran Turismo 5 will be out November 2.