My RC model car, weighing under 20kg, keeps shooting in the air as soon as I press Play but everything goes back to normal when I increase the mass to, say, 500Kg. Anything below that value tends to mess up the behavior. Any idea on what kind of settings I should use here?
Reduce the physics timestep.
The cause of that behavior is the bad implementation of the damper in PhysX. Damper values impose the same forces no matter the mass of the vehicle. Try reducing the damper values to around the same value as the rigidbody’s mass.
I assume your RC Car Model is 1/10 or 1/8 in size.
I would highly recommend scaling the model (or do it in the FBX import settings) up, so that your RC car is the same size as a real car.
of course everything else has to scaled to (size)
And most importantly, set Physics.gravity to a (much) higher value… also scale this part.
Also don’t forget to find a tweak the forceAppPointDistance Unity - Scripting API: WheelCollider.forceAppPointDistance