The Navigation identification number consists of 16 numeric digits. In the car it is displayed as four groups of four digits separated by three hyphens (ie 1234-1234-1234-1234)
You can get the Vehicle ID from the car here Menu > Settings > Car > WiFi
Look for the following message: "Visit LEXUS portal (www.my.lexus.eu) or contact your local dealer. Remember this Navigation identification: nnnn-nnnn-nnnn-nnnn"
Confusingly, the actual online registration requires you to enter the 16 digit ID number with no spaces nor dashes and it would have been nice if the error messages had explained that.
The Terms and Conditions of using the system are absurd but you will need to agree in order to proceed. They are subject to the laws of Belgium, which is nice.
When all your details are entered, the Lexus site sends you an email with a link to activate your account. It took quite a while for mine to come through.
As part of the registration process you will be asked to create a user name and password. Since you will need to enter these details in the car as well, you might want to consider using all caps and numbers.
I soon wished Id used a more memorable (or easier to enter) password!
I had to enter and re-enter my username and password details several times until I managed to log in via the car. It took me a while to get my mobile hotspot setup sorted, but the car remembers all your login credentials provided there are no connection errors.
In use Ive found the mobile data demands of the system to be quite modest so far. This was something I was concerned about because of the cost, but Ive now removed all the in-car warnings about connection charges.
The additional parking and traffic information is worthwhile, but the Streetview and Panoramio functions havent been used much. In time I hope that the Connected Services will improve.