IMPORTANT NOTE:

If the scene reloads on its own, it is because the main car got stuck. In that case, just wait or reload the scene until it can get through the first curve. After that, it goes smoothly for some laps until it gets stuck again :P.

CONTROLS

C: Change camera

R: Reload scene

Based on this video by Sebastian Schuchmann:
ML-Agents 1.0+ Creating a Mario Kart like AI - YouTube