Here's a YouTube playlist where a guy made a self-driving vehicle in GTA V using Python.
It was also very interesting in the early days because you could see the agent getting much better day after day.
It looks like it still has a lot of improving to do to manage basic stuff like not accelerating into oncoming vehicles, but it's quite neat to see that its mastered the art of stealing another vehicle after writing its own off, which isn't something your average self driving neural network gets trained on.