The previous record was $3.09 for a litre of 91 petrol.
Green said the cheapest price in Auckland was $2.90 a litre.
He said that prices were the highest that they had ever been.
Meanwhile in Hamilton fuel costs anywhere from $2.64 to $3.04 a litre - a 40 cent difference across companies.
Wellington is not far behind with a difference of 30 cents, followed by Christchurch that boast a difference of 25 cents.
Green said that the national average was $2.84 a litre.
"$3.15 is the worst its ever been in the history of New Zealand," he said.
In March, the government scrapped fuel taxes for three months to help people cope with the rising cost of living when petrol prices rose above $3 per litre.
Nonetheless, prices have continued to rise.
Green remains unsure of when they will go down.
