New features in the Spec 2 update include an interior view for all standard cars and the option to save progress during endurance races.
Players will now be able to adjust weather settings, including incremental weather between the start and end of a race.
The update will also add 11 new NASCAR 2011 cars.
"The coming Gran Turismo 5 Spec 2 update is an update that contains the feedback from the users playing GT5 online every day," said series creator Kazunori Yamauchi. "We have added cars such as the newest NASCAR race cars, but many of the updates are those that improve usability and expand the field of game play."
"I believed from the initial release of Gran Turismo 5 that it would be the users that would make the game grow thereafter, and we added things like interior views for the standard models because there was a lot of request for it from our users. You could say that this update is the shape and form of GT5 that was created through the opinions of our fans."
Other new features include:
The update will be available as a free download from October 11.