The axis_forward:X / Blender-Z axle fix changed the reference pose but not the drive
(-2737 cm/s), and axis_forward:X also alters the shared character preset. Revert it.
The Chaos solver drives the wheel about the vehicle's Y (not the bone), and the
drive force is positive yet the car moves backward - the inversion is in the engine
torque / drive-force sign. Next: GetEngineTorque() sign or a SetupVehicle override.