MILLIONS of motorists have embraced new technology to save hundreds of dollars a year on their petrol bills.

Fuel is widely considered the no. 1 grudge purchase for most consumers. Many suspect petrol companies are taking them for a ride due to the incomprehensible "price cycles" in all the mainland state capitals apart from Perth.

Then there's the cartel which dictates the international price of petrol. The Organisation of the Petroleum Exporting Countries, or OPEC, along with nations such as Russia, have conspired to cut oil output to elevate prices. The flow on? The cost of a litre of petrol rose 10 per cent in Australia in the last quarter of 2017.

However, the emergence of petrol websites and apps has for the first time given drivers a fighting chance.

In the final three months of 2015, the major petrol price apps had about four million hits, according to the Australian Competition and Consumer Commission.

In the same period of 2016 the apps attracted 20 million visits.

"It's a great opportunity for consumers," said GasBuddy Australia manager Nic Moulis.

These apps typically provide a map of nearby service stations' charges in real-time; some also advise on whether you should buy now or later.

If the advice is to buy now and you take it, you avoid the peak of a cycle, when prices shoot 20 cents per litre higher overnight.

Jess Walker fills up her “thirsty” car with petrol as her son Lachlan watches on at Bargain Petrol station in Erskineville, Sydney. This station has the cheapest petrol around. Picture: Brett Costello
Jess Walker fills up her “thirsty” car with petrol as her son Lachlan watches on at Bargain Petrol station in Erskineville, Sydney. This station has the cheapest petrol around. Picture: Brett Costello

If you put 50 litres in your car at the lower price, you save $10. Do that 10 times in a year and you are $100 better off.

The mapping function can deliver even greater savings - and more often.

The difference between the lowest and highest price in a local area is often greater than 10c/L and, in researching this story, was found to be as high as 38c/L. A commuter who bought 50 litres a week from the best-value station could save more than $250 based on the typical 10c/L saving.

The more you drive, the more useful these apps are.

For example, you may hit the road for work only to discover that prices have moved to the top of the cycle. Because not all stations move at exactly the same time, using the mapping function you may be able to find a servo that has yet to raise its prices.

"Petrol websites and apps are beginning to play an important role in providing price transparency and I cannot emphasise enough the importance of price transparency in enabling competition in the retail petrol market," said ACCC chairman Rod Sims.

"The more people that use these websites and apps, the more powerful a role they can play in helping consumers get the lowest prices."

Motorists who don't fight back are getting ripped off - ACCC research shows fuel retailer margins on bowser sales are high and growing.

All else being equal, this service station should be dead quiet. It's early on a Tuesday afternoon - commuters are still at work and the school run hasn't yet begun.

But instead it's pumping, so to speak, as cars, taxis and utes queue up for bargain fuel.

Manager of Budget Erskineville Dimitri Petrou keeps prices low - very low.

According to data from the NSW Government's FuelCheck website, this servo in Sydney's inner west, is as much as 29 cents a litre cheaper than its competition.

On a 70-litre tank, that's a saving of as much as $20.

And that's great news for motorists such as Newtown mum Jess Walker.

She describes her Jeep Wrangler as "thirsty" compared the Toyota Corolla she used to have.

"So it's great to get a decent price," she said, while filling up with ethanol-blended unleaded.

The growing Budget chain and others like it in other states are disrupting the market and staying low when rivals go high, giving motorists the chance to keep their car running costs at a reasonable level.