The Minister for Energy and Resources says she's had enough of petrol companies ripping off motorists.
Megan Woods told The AM Show she's hoping to give the Commerce Commission the power to investigate huge discrepancies in price across the country.
"If you live in the Wellington region or the South Island, you may well be paying more to fill up your tank than if you live in Auckland.
"But then it's not as simple as that, because depending on what suburb you're in in Auckland you might be paying a different price.
"All the signs are pointing that we do need to refer this to the Commerce Commission.
"But it's not even as simple as that because we need to make some changes to the Commerce Act to give them the power to do market studies."
A Ministry of Business Innovation and Employment fuel market report is due out on Wednesday, and Ms Woods says it may shed some light on the situation.
"All the evidence I've seen is pointing to the fact that people aren't paying a fair price at the pump depending on what part of the country they're in.
"People are just seeing the unfairness.
"We're determined to do the work to get to the bottom of this."