The project is starting to look promising :)
I was wondering if you had any plans to open source GDSim, especially since it's distributed on a pay-what-you-want scheme right now (so there wouldn't be much to lose from a monetary standpoint). I've seen many people asking how to implement better vehicle physics in Godot, but figuring out the implementation by yourself is a lot of work. In this way, GDSim could be a helpful learning resource.
(Don't be afraid of your code looking unprofessional, it can always be improved in the future :))