Mr Key said the decision to move the V8s to Auckland was now - with the exception of getting Ministry of Defence approval to use the land - in the Auckland Council's hands.
Former Hamilton City Council chief executive Michael Redman, who was instrumental in bringing the event to Hamilton, now heads Auckland Tourism Events and Economic Development for the Super City.
Mr Key had no concerns Auckland would find itself in the same position as Hamilton where, after five years, ratepayers have spent $40 million on the event, $22 million of which is debt-funded.
The Prime Minister said there had been "a bit of dialogue" between his office and the V8 Supercars Australia management about the move to his Helensville electorate and setting up a 3.5km track on the Whenuapai Air Base from 2013.
"There's a facility there [in Whenuapai], it's not without its complications as well, but it would certainly work and attract a large audience."