Immobilizer Generation 4
Many newer cars including all of the Golf/Jetta (1K) Models use Immobilizer 4. There are different varieties of Immobilizer 4 Implementations, some of them don't show a 14-digit Immo-ID anywhere, but rather a "Challenge" Value in Advanced ID. This Challenge changes every Time Terminal 15 (Ignition) is cycled.
As a general rule, VW models using Immo 4A (with Adaptation) may have Serial Numbers that contain VWZ (for Example VWZ7Z0G7051888). VW models using VWX (for Example VWX7Z0G7051888) "or ones without a Serial Number shown at all, do not use Adaptation and will have the revolving "Challenge" Value in Advanced ID. Those systems using a Challenge Value are not considered supported at this time.