As petrol prices surged across Adelaide on Wednesday, with some outlets selling it for $1.77 a litre, Attorney-General Vickie Chapman urged motorists to make use of smartphone apps to cut costs.

"With such a discrepancy in the current market, motorists filling up a 60-litre tank could save around $25 if they can locate and choose the cheapest option," Ms Chapman said.

"I urge South Australians to take up this offer, and use it effectively, especially during periods of price spikes," she said.

The scheme requires retailers to update their price information to a central aggregator within half an hour of posting it or face fines of up to $10,000.

So far 270 compliance checks have been conducted with four outlets issued with warning notices and two with fines.

The Royal Automobile Association said its app had been accessed around 790,000 times since March, with a recent survey showing users could save an average of $337.20 a year.

"Fuel prices always vary and when prices spike, the difference between service stations can be up to 50 cents per litre," fuel expert Mark Borlace said.

"The reality is, if you're not using an app you're probably losing money."

Australian Associated Press