Fuel retailers continue to battle it out for customers as price wars rage across the country.

The Automobile Association says the average price for unleaded 91 is a $1.93 a litre but some service stations are knocking up to 30 cents off that.

AA's Petrol Watch spokesman, Mark Stockdale, says there have been huge disparities in fuel prices within regions and within suburbs.

"So only really in the North Island or the Upper half of the South Island, really any area where there is a Gull service station generally."

Stockdale claims Gull has always had the lowest fuel prices, which has a 'flow-on' effect on neighbouring service stations.

Drivers using premium fuel are being warned not to be wooed by the price of 91 as they pass by a petrol station.

Mark Stockdale said if 91's at a low rate, motorists shouldn't assume there's a knock on effect on 95 or 98, because it's often not the case.

"Those motorists who use premium fuel, they've got to do a little bit more work to figure out what the price is. They've actually got to drive in and have a look at the pump."

Stockdale believes the Government needs to make it mandatory for all prices to be displayed on fuel price boards.