The Stunt Race Creator, is what Rockstar calls the new track editor that arrived with the most recent update of GTA Online. A new tool to create impossible tracks in and over Los Santos with loops, tubes, jumps and slopes.
Grand Theft Auto V online multiplayer turnet into a stunt racer game in July and the developer is now fleshing that out. The Stunt Race Creator is a simple-to-use editor with over 250 different items that include, not only track-parts but also "dangerous obstacles like flaming rings, speed boosts, oversized soccer balls, bowling pins and more". There is also an official PDF guide to assist you in your creative process and Rockstar promises official contests in the near future.
The update also brings a new Adversary Mode called Entourage. The main difference is that only one person on the defending team will see what is going on in the map, so the others (bodyguards) must rely on his or her guidance.
"Entourage requires tactical teamwork for Bodyguards to transport a well-armored and armed Target to a designated Extraction Point, all the while battling a team of Assassins attempting to take down the Target. The Extraction Point along with all Assassins are only visible to the Target on their radar - the Bodyguards must rely on communication to safely transport the Target and themselves to the goal."
For more information check the Rockstar News feed.