The scheme, which would emulate Western Australia's 'FuelWatch' despite a few distinct differences, would see retailers required to declare their fuel prices by 6am every morning and lock them in for 24 hours.

As of Monday, the average price for unleaded petrol in Canberra was about 145.9¢ per litre, compared to 125.2¢ per litre in NSW. In Belconnen, it was 146.4¢ per litre, compared to 112.5¢ in Bowral - or about 33¢ per litre more.

"Canberra is the most expensive place in Australia to buy fuel ... we're being ripped off and the current government refuses to take action," ACT Opposition Leader Alistair Coe said.

“A Canberra Liberals Government will trial real-time monitoring of fuel prices to improve transparency of the system and encourage healthy competition among retailers."

A recent report by the Australian Competition and Consumer Commission, which looked into the outcomes of WA's FuelWatch - introduced in January 2001 - found the scheme was helping save Perth motorists up to $520 a year.

This finding, though, accounted for the fact that Perth's petrol pricing was hugely controlled by the city's price cycle. If motorists filled up once a week on Mondays, the low point of the city's price cycle, rather than at the high point on Tuesdays, they would save the most amount of money.

Such a cycle would be unlikely to occur in the national capital considering the lack of competition between retailers, but the scheme would still make Canberra's fuel market more stable, predictable and transparent, ACT Liberals say.

WA's scheme also sees prices made public on FuelWatch's website at 2.30pm and come into effect at 6am the next day, rather than being declared at 6am on the day, to be locked in for 24 hours.

This allows consumers to compare prices and make a decision on whether they fill up at the pump that afternoon, or wait until the following morning.

"We will trial a 6am price lock and are open to experimenting with other times if these result in lower prices at the petrol pump," Mr Coe said.

ACT Chief Minister Andrew Barr said this morning fuel watch schemes could not guarantee lower prices at the pump, instead encouraging motorists to use independent websites to track prices.

"We know from [the] Petrol Spy [app] that fuel is cheaper in Fyshwick, Pialligo and Majura Park. Motorists can save between 10¢ and 25¢ a litre at the Caltex, Mero and Costco service stations in those areas," he said.

"Duplicating Petrol Spy with a Government run FuelWatch scheme would have administrative costs associated with it, and this cost would be met by Canberrans."

It is unclear how much it might cost to run a real-time fuel watch scheme in a jurisdiction as small as the ACT, but the most recent attempts to establish such a scheme came in 2008. The Rudd government planned to roll out FuelWatch nationwide at a cost of $20.9 million over four years, but the legislation did not pass the Senate.

Chief Minister Barr also warned that imposing a 24-hour rule on fuel retailers could potentially reduce competition across the territory.

"It is worth noting though that the consistent view of the ACCC has been that 24-hour notification rules can actually reduce competition because they mean that a supplier who discovers their price is a little higher than another nearby cannot lower them for at least a day – as opposed to doing so immediately as would be the case now," he said.

"This is a risk that would have to be addressed in any 24hr price-fixing scheme operating in the ACT."

The National Roads and Motorists' Association is lobbying the ACT government to introduce real-time price monitoring similar to the Fuel Check system that has operated in NSW since 2016.

Queensland is also trialling real-time price monitoring, but WA's FuelWatch system, which the Liberals' scheme would be modelled off, is the only one in Australia that employs a 24-hour price lock rule.

Mr Coe says he will write to the Australian Competition and Consumer Commission to request an investigation into Canberra’s petrol prices.

Chief Minister Andrew Barr says he has done the same as "price gouging and market failures continue to hurt ACT motorists".

with Blake Foden