Oil companies Shell, BP and Caltex have dropped the price of petrol in New Zealand by 4 cents a litre on Wednesday.
A litre of unleaded is now $1.96. Diesel has dropped 6c a litre to $1.54.
Mobil says it is still assessing the market.
The moves follow another fall in the price of oil overnight.
US crude dropped $US4.50 to $US91, its lowest price since February.