The DLC for Sonic & All-Stars Racing Transformed introduced new content to the game, including additional characters, tracks, and cosmetic items. One of the most notable DLC packs was the "Transformers" pack, which brought characters like Optimus Prime and Bumblebee into the game. Another significant addition was the "Year 2 Content Pack," which included new tracks, characters, and vehicle types.
The Xbox 360 Marketplace for the console has largely been shuttered, meaning the official window to buy this DLC is long closed. For RGH users, this isn't a problem, as you can manually install the DLC files. dlc sonic all stars racing transformed xbox 360 rgh top