@Override
    public void write(JmeExporter ex) throws IOException {
        OutputCapsule capsule = ex.getCapsule(this);
        capsule.write(tuning.frictionSlip, "frictionSlip", 10.5f);
        capsule.write(tuning.maxSuspensionTravelCm, "maxSuspensionTravelCm", 500f);
        capsule.write(tuning.maxSuspensionForce, "maxSuspensionForce", 6000f);
        capsule.write(tuning.suspensionCompression, "suspensionCompression", 0.83f);
        capsule.write(tuning.suspensionDamping, "suspensionDamping", 0.88f);
        capsule.write(tuning.suspensionStiffness, "suspensionStiffness", 5.88f);
        capsule.writeSavableArrayList(wheels, "wheelsList", new ArrayList<VehicleWheel>());
        super.write(ex);
    }
used internally

@return the pre-existing instance
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsVehicle.java