Sony has decided against releasing a retail boxed version of Gran Turismo HD. It'll be released as a demo.

Gran Turismo HD Concept screenshot

The free demo will be released on the PlayStation Store from December 24 and will be available for a limited time only. The release is currently only scheduled for Japan and will feature ten cars and one track - albeit with two layouts.

Game modes will include Time Attack and Drift Trial modes, and you'll be able to upload your times using a Network Ranking feature.

Those hankering for real next-gen Gran Turismo will have to wait until 2008, when Gran Turismo 5 is expected to hit store shelves.