What free PS3 demo was the first Gran Turismo release on that console?

Gran Turismo HD Concept was the first Gran Turismo release on PlayStation 3, arriving as a free downloadable demo.

Sony released the demo through the PlayStation Store on December 24, 2006. It was designed as a technical preview rather than a full series entry, offering a small selection of content to showcase the new console’s high-definition capabilities. The demo included ten cars and the Eiger Nordwand circuit, with Time Trial and Drift Trial modes.

The name can cause confusion because Gran Turismo 5 Prologue followed it as a more substantial preview release. Gran Turismo HD Concept was also connected to an abandoned Gran Turismo HD project. Polyphony Digital ultimately redirected its development effort toward Gran Turismo 5, making the free demo a brief but historically important first step for the franchise on PS3.