Price Cycling for Unleaded Petrol

I've noticed that the price of fuel changes during the week, and that this has become so common that it's accepted as normal.
However I thought that some discussion of this topic was warranted. Considering the price of fuel in general, anything that helps reduce our petrol bill is handy.
The figures in the graph are for NSW unleaded fuel price average costs for each day taken over the last six weeks. The average is taken from approximately 190 petrol stations across the State.

Summary of the Graph 

Fuel is cheapest on Tuesday and Wednesday and the most expensive on Friday, Saturday and Sunday. The price variation has been from eight cents per litre to three cents a litre.

A few more facts about this price cycle:

The price of unleaded petrol has risen by $0.35 in the last year.
The price of diesel has risen by $0.53 in the last year.
The price of LPG (liquid petroleum gas) has risen by $0.17 in the last year.
The price of E85 petrol in my local area has risen by $0.05 in the last year.

None of the fuels, other than unleaded petrol, exhibit the cycling phenomenon in the price.

How to reduce your automotive fuel bill?

If you use ULP or E10, fill up on Tuesday or Wednesday.

For a 20% reduction, use E85:

There are some tables of cost and economy using E85 in other articles that are on this site: http://www.flexfuelkit.com.au/articles/2/1/My-Conversion-to-E85/Page1.html