What happened to them increasing garages to possibly as many as 82? They announced it in 2019. Thought they might have given an update.
I think the number of race cars allowed is not only tied to the number of garages. I have read somewhere (don't remember the source, was many years ago) that the max number of cars allowed on each racetrack is set by FIA-rules and depends on the size of the track and the speed of the cars (slower GTs allow a bigger grid than F1 cars). I also remember that in the group C days this limit was about 70 cars for the 24h track, which was never reached. But may be someone knows more? Currently Le Mans has a grade 2 FIA license.