The Hamilton City Council has ordered an independent review into the cost of the Super V8 car race, which is more than double previous estimates.
Initial figures had put the cost of the Hamilton-400 over the past three years about $11 million, but the council now says the event cost it more than $30 million.
Last year, the three-day event attracted more than 100,000 people, and the council has estimated it brings about $20 million each year in benefits for the local economy.
A report released by the council shows the cost of the event over the past three years has been $27 million, plus additional confidential payments for event sponsorship.
Julie Hardaker, who has been the mayor since October, says the cost is a lot more than anyone had previously thought.
Ms Hardaker says while the event brings benefits to the local economy, the council has received little over $1 million in income from the event.
The Waikato Chamber of Commerce believes the cost has been worth it, as the event encourages many into the city and benefits many businesses, particularly restaurants and accommodation providers.
The independent review is expected to be completed in the new year.