Sony has responded quickly to shoot down rumours that Gran Turismo 5 has a install which could take close to an hour. While the game does include a 6.4GB install, it is entirely optional.
"GT5 gives users the option of an install," stated Sony. "This makes loading times throughout much faster but is not a requirement when first playing."
The statement also goes on to say that the install, should users wish to install it, will take place over time in the background and that the only mandatory install is 256MB, considerably smaller.