Hey, time poster here. Been playing since gt3, and love the series. 5 was kind of weak at first but has gotten better...so i'm hoping this creator takes off and becomes more than a generator.
Like the GPS idea! (Other threads indicate its "a go" i guess.) I have some amazing roads from michigan that i would love to see and i know they would fit in the games size limits. That could be the easy approach and they could do a advanced editor with more detailed tools. Also, used to drive from Chrysler at the Chelsea Proving Grounds...many a roads...and could recreate them all from the road maps with mileage values.
But, realistically i think it will be more generator still.
Hoping more info surfaces in the next couple weeks and along with read everyones posts...i'm sure its answered.
Course Maker
This feature, available at a later stage through an update, will allow you to create your own custom tracks that can be driven in the game. Additionally, in another update we will add the possibility to generate a track by capturing the GPS coordinate data of a mobile app while you are driving that course. This GPS-generated tracks will be available in the game as playable content.
http://www.gran-turismo.com/us/products/gt6/
The only question now though is when the app and course maker will be released. Hopefully day 1 but I doubt it. But if the A-Spec and the rest of the features are complete enough well the course maker could wait. Hopefully as GoingMissed said we have more control over the course maker so it becomes a tool instead of a generator.