Rockstar has fulfilled their promise saying that they would release a track creator on August 2nd.
Well, August 2nd has come around and lo and behold, the track creator is live. According to vg247.com, you won’t even need to download any patches, as the update is activated on the Rockstar server-side of things.
This track creator comes as a part of the Cunning Stunts DLC which saw thirteen new cars, numerous new races and outfits galore (and it’s free). Complete list here.