Thanks to everyone for the information supplied.
Am I right in thinking Android Auto does not need the car to have internet connectivity because it uses the phone's internet and the phone is plugged into the system with a cable? If this is correct then it may have been confusing me when trying to understand what car internet connectivity brings to the party.
I did realise that the car could get it's internet by by using a phone's hot spot WiFi provision.
Thanks Paul for listing the features that the car built in system uses the internet for. (Fuel, weather, live traffic info etc)