Petrol prices have been cut for the third time this week.
Z has cut its price for unleaded 91 to $1.73.9 per litre.
That follows a cut of 3 cents yesterday and a cut of 3 cents on Tuesday.
Crude oil has plunged to below US$27 a barrel this morning. But the New Zealand pump price is governed by international refined prices. The refined prices have not fallen by the same percentage as crude oil.
The AA said yesterday that it believed there was room for a price cut of up to 4 cents per litre for unleaded 91, based on a fall of 10 cents per litre this week in the petrol commodity price.
The New Zealand dollar has also made gains this morning, with the Kiwi rising to 67.00 US cents, from 66.69 yesterday.
The price for diesel remains unchanged at $0.96 per litre, the lowest it has been since 2007.
The AA points out that around half the cost of a litre of petrol is made up of various taxes, whereas diesel users pay levies through road user charges.