I've come from a BMW Z4 (children came, two seater had to go) where the BMW workshop software is widely leaked/available online (DIS Diagnostic and Information System). I'd hoped it was the same with VW's' but now realised there is no freely available equivalent.
The penny has just dropped the the cable is effectively the software license! So $250 gets a cable and the licence.
On the upside in a VW people let me pull out at junctions, unlike in the BMW
Thanks