Lewis Hamilton will appear in GT Sport as your driving mentor
In GT Sport, it looks like you'll be learning from one of the best F1 racers in the world as you play, as 3-time F1 World Champion Lewis Hamilton will be appearing in the game to be your mentor. He'll be giving racing tips for you to get the best racing times possible.
Announced earlier in a video on YouTube, Hamilton will be "the mentor and Maestro who will lead and guide the players" in GT Sport, although the extent to which he'll do this is unconfirmed. The video itself only shows off Hamilton driving with Gran Turismo series producer Kazunori Yamauchi and giving him some brief tips, mostly on how to take corners.
This trailer released just as the time-limited demo for GT Sport ended, so hopefully you got some time to try that out before it closed. Hamilton didn't appear in the demo, so we can only assume he'll be added in as a mentor by the time the full game releases.
The announcement post for Hamilton's involvement with GT Sport mentions his "driving footage, theories and episodes" will be available, while the trailer says you'll be able to watch him set reference lap times, so a key part of his advice looks to come in the form of his own experience playing the game, allowing you to copy and imitate his driving.
Hamilton himself is one of the best-performing racers in history, second to only Michael Schumacher in his number of Grand Prix victories. At one point, he was the youngest Formula One World Champion in history, too, so there's few better than him to watch.