This is what I tinker with when I'm not working on my main project (non-Godot).
The goal is to have something like the 2005s era Need For Speed games or Burnout Paradise, but with procedurally placed stuff so that the poor level designer does not have to place everything by hand.
The code is slowly being uploaded to GitHub - https://github.com/Zireael07/FreeRoamRoguelikeRacerPrototype
Currently the basic procedural generation of road segments is in, as well as their placement (two kinds, a straight with a curve left and a series of curves). I have also figured out how to place props (buildings, road signs) procedurally but this is not in the repo yet.
Player and AI use the same physics under the hood. The AI drives to a target, one target per AI. I have a version where the AI pathfinds using a procedural navmesh (that matches the road mesh) but this is not committed yet.
I have also figured out how to draw a 2D minimap using Controls (to avoid rendering the whole level again). The minimap in the repo works like a radar, showing the AI's positions compared to yours. In the test version, it's slightly more advanced and uses shaders to achieve panning (not shown in the gif) and a circular mask. The minimap texture is just a test texture, but I plan to use Image.setPixel() to draw roads based on the data that the procedural generator outputs.
The gif shows my test project (so it has the props and the navmesh and the better minimap, but on the other hand it also has a ton of testing/debugging stuff that the version in the repo doesn't)
P.S. The project is being made in 2.1.3, hence some rendering glitches. I plan to move to 3.0. at some point though.