To reproduce:
1. Open the project
2. Open the scene "Demo C#"
2. Drive the car around a bit
3. Notice that it behaves as expected (doesn't tilt without a reason, etc.)
4. Go to the script "VehicleParent.cs"
5. Comment out line 368 "rb.inertiaTensor = rb.inertiaTensor;"
6. Drive the car around for a bit.
7. Notice that it tilts and sometimes turns over for little to no reason.

Expected behaviour: the line rb.inertiaTensor = rb.inertiaTensor; has no effect.

Regression started in 5.3