The Australian Competition and Consumer Commission (ACCC) has commenced an investigation into whether petrol companies illegally share pricing information in a way that reduces competition. That doesn't mean we'll see a fixed price for petrol, but it could see further shake-ups in the typical pattern of petrol becoming cheaper or more expensive on given days.
Picture by Newtown Graffiti
However, the ACCC can (and will) intervene if it believes competitors are colluding in order to stop price competition. Say a group of large businesses all agree that they won't charge less than a given price, or that they'll only reduce prices on a given day. That's a clear violation of anti-competition law.
The ACCC is now formally investigating whether large petrol companies have indulged in that kind of behaviour. As its announcement notes:
The petrol price sharing arrangements allow for the private and very frequent exchange of comprehensive price information between the major petrol retailers. The ACCC is concerned that this allows petrol retailers to quickly signal price movements, monitor competitors’ responses, and react to them.
We're not likely to see a major outcome from this for a while; the announcement notes that the investigation will take "some time". However, the mere fact an investigation is taking place may put petrol retailers into "best behaviour" mode, which might mean we see bursts of actual competition, not co-ordinated pricing cycles.
The most recent investigation into petrol prices by the ACCC suggested that petrol prices rose by eight cents a litre last year. If you're trying to save money, it definitely helps to buy on the "cheap" days, but you need to recognise that these change over time. The ACCC offers a weekly update on which days are cheapest in major capital cities.