Fair Go: What's the best day of the week to fuel up?

Garth Bray
Source: Fair Go

Friday is one of the busiest days at petrol stations but it could also be the day when it costs you the most to put the fuel in your tank.

"Our year to date data for 2022 for New Zealand indicates an emerging trend that prices tend to be higher on Fridays and lower on Sundays and Mondays," fuel card company Fleetcor told Fair Go.

It publishes daily data on prices paid at stations across New Zealand on its Pricewatch website and responded to Fair Go's request for some high-level analysis.

That contradicts everything fuel companies are telling us - Z, BP, Mobil and Gull.

The four big importers insist that there is no weekly pricing cycle, rather a host of very competitive local markets where people can pick from several different fuel retailers and a host of loyalty schemes and regular discount days..

There are busy days of course. Worldline tracks electronic payments by retail sector.

It says Wednesdays, closely followed by Fridays, are the days on which most consumer spending tends to happen at fuel retailers. The figures include everything bought at the service stations but fuel would make up the vast majority of what's spent, especially at current prices.

So if Friday is both busier and maybe more expensive, do we need to avoid a Friday fill? The AA would prefer to see more data before it declares there is a best or worst day, but its chief fuel watcher Terry Collins is keeping tabs.

"I know in Australia they often complain about they put the prices up before a holiday, or before the weekends. It seems to be a pattern. I don't know whether that's being developed here or not."

Collins says the market is subject to extreme pressure and volatility now ahead of EU sanctions to ban using Russian oil. That could make oil from anywhere else more expensive. Collins adds that oil company inventories are low worldwide.

The whole industry is running on E for enough - just like a motorist who needs to fill up - so it will have to accept higher prices.

"Depending on what day the oil company bought their fuel, whether it was the Monday or the Friday, some of them might have to reflect a 10c difference in price just based on when they purchased their fuel," Collins says.

All of that in turn may push fuel prices even higher which means more inflationary pressure, given how the price of fuel affects almost every bite we eat and everything we buy or sell in our highly carbon-dependent economy.

That could figure in the Budget later this week. On 14 March, Prime Minister Jacinda Ardern announced a 25c a litre cut in the fuel excise duty (plus GST) for three months and that cut is still set to expire next month.

"I would expect if the prices continue to go up that they must seriously look at perhaps keeping some of that excise duty off, otherwise the inflationary pressures will become very significant," says AA's Collins.

Keeping the cut to keep prices from rising would put pressure on the Government's books - the duty collected helps pay for transport investments - and the Government may argue it's already doing more to control our exposure to runaway oil prices by ditching fossil fuels through its Emissions Reduction Plan announced this week.

But those are long-term measures; in the short term every day will still be a very expensive day to fill your tank - just how much and on which day might be worth careful attention.