They are adding events every week, and three new cars monthly(I believe).
I wish they added some new circuits, that would be great. But it's absolutely great game. Some people that are using VR and have time for scapes, etc. are posting pictures of details on the car, and it's just unbeliveable attention do detail. I don't think it's possible to graphics to be better actually.
https://www.reddit.com/r/granturismo/s/309qzzJdo8