The Auditor-General has found no grounds to investigate the way Auckland Council decided to host the V8 Supercar event.
Several councillors complained they had been given inadequate notice and information before they voted in July this year.
However, the Auditor-General has found most of the complainants misunderstood their role in the process.
The office says the decision to sponsor the event had already correctly been made by the council's events agency.
It says the wording of the council agenda caused confusion about whether councillors were making the decision, or simply being briefed.
A round of the Australian V8 Supercar series will run at Pukekohe for five years with $10.6 million of council support.