Motorists in Sydney and Brisbane are enjoying the lowest petrol prices in weeks, but those hoping to snag a cheaper tank of fuel will need to get in quick as bowsers begin to soar again.

Figures from the National Roads and Motorists Association (NRMA) show average petrol prices across Sydney have plunged from a high about $2 a litre late last month to just $1.62 a litre.

Separate figures from comparison firm MotorMouth show a similar trend in Brisbane, where average petrol prices have fallen from a high of $2.01 a litre to just $1.64 earlier this week.

Melbourne, meanwhile, is on a different track to Australia’s two other east coast capitals, with prices only recently coming off peak, falling to about $1.84 a litre this week, MotorMouth data shows.

But NRMA spokesperson Peter Khoury said motorists wanting to make the most of the cheaper bowser prices must act now, with the latest data showing prices are rebounding in Sydney and Brisbane.

“Sydney has started to turn; the average price has gone up 3 cents per litre overnight,” he said.

“It goes up three times faster than it falls, and we’ve seen that over the past 24 hours.”

There are still cheaper service stations available though, with NRMA data revealing retailers in some parts of Sydney are still selling petrol for as low as $1.49 a litre.

Khoury said that underscores the importance of shopping around, ideally with a fuel comparison app – something that the consumer watchdog recently endorsed in a report on petrol markets.

ACCC data shows motorists can save hundreds of dollars a year shopping around for petrol and timing purchases at the lowest point in the cycles that define prices up and down the east coast.

The regulator has noted the latest market shift in Sydney and Brisbane in its latest fuel market report this week, with prices in both capitals still far below the average in the past 45 days.

The good news is that the peaks and troughs of the latest petrol price cycles recently have been markedly lower than those seen earlier this year, when prices routinely went past $2.10 a litre.

That’s reflective of a slight easing in global oil prices that has begun to flow through to bowsers in Australia, though it can be hard to tell because bowsers are fluctuating hugely month to month.

Source: ACCC.

Khoury said it’s often difficult for motorists to navigate the wild fluctuations in prices, which more often than not forces them to pay more.

“The price cycles consistently work against motorists,” he said.

In other cities outside the east coast market conditions are different.

Prices in Adelaide are at a low point of about $1.56 a litre on average, meaning it’s a good time to buy.

In Perth, where petrol prices are regulated, the cheapest day to buy fuel is on Tuesday and the most expensive is on Wednesday; prices then fall gradually between Wednesday and Tuesday.

Average petrol prices across Perth hit a low point of $1.61 a litre on Monday and will fall further today before shooting back up tomorrow to somewhere closer to $1.90 a litre.

In Darwin petrol prices are much more stable in general and are hovering near $1.71 a litre, which is down from $1.74 per litre at the end of last month.

Down south in Hobart petrol prices are about $1.72 a litre on average, which in a similar vein to Darwin is down from about $1.80 at the end of last month.