The retail price of petrol dropped by four cents on Wednesday.
BP dropped its price of 91 octane - the second fall this week - and it was followed by Shell, Caltex, Mobil and Gull.
The price of unleaded petrol at BP, Shell, Caltex and Mobil service stations is now $162.9 a litre while it is $1.619 a litre at Gull.
BP says it'll pass on the benefits of lower prices to motorists as quickly as possible and will continue to monitor international prices on a daily basis.
Gull says the drop in international refined combined with a steadying New Zealand dollar allowed the drop.
The price of diesel is unchanged.