It may not be possible to register the Bentleys or Maserati in Australia (or get a Vehicle Import Permit) if the vehicle does not have an Australian ADR plate.
"The importation of a road vehicle (that is nonstandard or does not have an identification plate) without a vehicle import approval is prohibited under the Motor Vehicle Standards Act 1989. It is an offence with a maximum penalty of 120 Penalty Units."
I don't think they want you to do that! Commonwealth Penalty Points are now $210 each, so 120 Penalty Points will cost you $25,200 plus the cost to re-export or destroy the vehicle.
I suspect the details, VIN numbers etc of those vehicles would be well known to the Australian authorities.
https://infrastructure.gov.au/vehicles/imports/