Last year their fuel supplier changed to Viva Energy who simply charges more than Shell, when Shell was the supplier. Coles chose to maintain margins rather than subsidise their margin to keep/grow market share.
As you and @fred123 previously posted Blind Freddy has the answer to high prices. Shop around 
Perhaps we and our buying habits are why competition doesn’t work here like it does in most countries?
It is cynical marketing at its best. The cycle has been well described so I’ll not do it again, but if you consider how often the average motorist needs petrol versus the days in a cycle, it helps the petrol companies sell at a higher average price. Some will be caught out by the sudden $0.20+ rise and just need to buy. When the cycle is unpredictable (eg 1 week, 2 weeks, 3 weeks, 4 weeks, at random) the average price will be higher than when the cycle is predictable (eg consistently 2 weeks when motorists can plan ahead do minimalist top ups).
As it is, most will bite the price bullet at least some of the time and move on because they have as much chance of winning as losing the price war.
Diesel’s as low as 142.9 in Brisbane! Down from the whopping 174.9 peak from a couple of weeks ago. Maybe diesel is starting to be affect by this apparent fuel cycle? With my high-capacity fuel tank, low mileage, and less-than-average-km driven vehicle, I should be able to beat any price cycle that comes our way 
More from the ACCC:
Main points from the link:
Main findings from the September quarter petrol monitoring report
- In the September quarter 2018, average retail petrol prices across the five largest cities were 146.7 cpl, an increase of 1.5 cpl from the previous quarter.
- Average gross indicative retail differences (GIRDs) in the five largest cities decreased to 10.4 cpl in the quarter. GIRDs are the difference between average retail prices and average wholesale prices, and are a broad indicator of gross retail margins.
- Retail prices in Brisbane remained the highest of the five largest cities. The average retail petrol price in Brisbane in the quarter was 148.8 cpl, which was 2.6 cpl higher than the average across the other four largest cities.
- In the three other capital cities (Canberra, Hobart and Darwin), prices were always higher than in the five largest cities.
- The average differential between petrol prices in regional locations monitored by the ACCC and the five largest cities was 6.4 cpl. This was 1.5 cpl higher than in the June quarter 2018.
- In the September quarter 2018, diesel and automotive LPG prices in the five largest cities increased. Average retail diesel prices were 154.6 cpl, and automotive LPG prices were 85.2 cpl in the quarter.
If one lives in Queensland and is a RACQ member, until 31 December 2018 one can save up to $0.06 off per litre at Puma service stations:
Note: The $0.06 off apples to Premium Unleaded 95 and Premium Unleaded 98. Other fuels have a $0.04 discount.
More sage advice from the “consumer defenders” at the ACCC.
Along with all that urging to delay filling up, is the ACCC also urging us to delay going away on our holiday trip too!
If only the ACCC knew how do do comedy properly? 
… doesn’t everyone keep 3500 km’s worth of fuel on hand just so they can buy it 2 cents a litre cheaper? 
I like that the RACQ has partnered with an independent retailer. NRMA has partnered with Caltex, so even after the discount, I’m better off buying fuel elsewhere.
Which “Sage” would be most appropriate I wonder?
Noted Puma was $1.207 this morning for unleaded 91 before discount.
We drove from Cairns to the Sunshine Coast hinterland on 10th & 11th of this month and back home on 26th & 27th, and we refuelled at a number of towns along the way.
The cheapest fuel was in Gympie at 125.9 c/l for U91 at all outlets except Coles Express.
The most expensive fuel was at Coles Express in Emerald at 159.9 c/l but the BP at the other end of the block was 146.9 c/l.
Back home the price has fallen to 130.9 c/l at the United servos with a Caltex matching them and a Puma undercutting them by 0.02 c/l.
Needless to say, as usual, Coles Express is the most expensive in town, but no surprise there.
My best tip for saving money on fuel in Cairns is to avoid Coles Express like the plague and drive to our local United to get the cheapest U91 fuel in town.
Also, great pies since United took over the twice failed Pie Face group and added a Pie Face bakery in the store.
I don’t agree with the 90km/110km fuel usage comparison in the case of our Honda CRV. Around town, it is over 10 L /100 km. In 80 km zones. It is under 10 L / 100 KM. On long trips from Cairns to southern Qld via Charters Towers and Emerald, where a lot of the highway has 110km/hr zones, it gets down to 7.8 L / 100 km.
Another way is to walk or use a bicycle for short trips. Many cars travel often only short distances (e.g. drive to the local shop nearby, drive from one side of the road to the other when shopping etc).
Also one can use public transport if it suits. While it may take a little longer, it can be just as convenient especially of the public transport drops one off outside or under the place one wants to visit.
Looks like Coles Express may have finally woken up to the fact that having the highest fuel prices around does not mean higher profits.
Yesterday our local United was 121.9 for U91 whilst Coles Express was 135.9 but it is a bit hard to gouge all that extra margin when the pumps are not being used whilst customers continue to queue to get to the pumps at United.
… haven’t noticed any improvement in remote areas 
No huge improvement on the Gold Coast either until the just recent petrol prices drop, but diesel remains high.
The games continue. Bris-Vegas at the end of last week Friday saw regular unleaded down to $1.15 to $1.20 without discount.
Come Sunday $1.40 or higher. Really!
We sampled Qld regional fuel prices on a trip 10 days back. Typically these did not reflect the lows of SE Qld. They were high in all the usual places, eg Clermont. And cheapest at the major regional coastal cities. Except Rockhampton which is always unreasonably expensive compared to Gladstone just down the highway?
U95 here 1.62-1.80 (we don’t have U91 - just LAF which nobody much uses)
Diesel 1.55-1.70 …
That variation in a town where every fuel outlet would be within 5 km of the CBD … not much in the way of variation at each outlet over time, and everyone knows the bad ones, but they still seem to do good trade …
Something extremely suspicious has occurred with fuel prices in Cairns very recently.
When I filled up at our local United on 13.02.2019, U91 was 120.9/L whilst Puma and Caltex were around 124.9/L a few days ago, and Coles Express was around 130/L.
Today I saw that all the Coles Express, Shell, Caltex, Mobil, BP and Puma outlets were all 129.9/L and the United outlets were 128.9/L.
After introducing the first real competition in Cairns in June, 2017, it appears that United has rolled over and got into bed with the local cartel.
When United arrived, I said that if they were to leave tomorrow, the local cartel would be straight back to their old tricks the following day, but it appears to have happened without United leaving.
Looks like it is time to unleash the ACCC onto this disgusting price fixing scam.
Oops. I forgot to bring some teething rusks for them.
