Auckland Council members have now viewed confidential documents previously withheld from them about a plan to host the V8 supercar series.
The council last week announced it will contribute $10 million to stage the event for five years at the Pukekohe circuit, starting next April.
One of the documents was a due diligence report on the financial background and other details of the event's Australian promoters.
Some councillors last week objected to the council's events agency not making available all the background reports on the deal, and set up a sub-committee to view the reports and monitor the deal's progress.
Five councillors and the chief executive have now met the events agency and approved the signing of a heads of agreement with the promoters.
Further legal and financial details are yet to be finalised.