So this week it's petrol-saving. Every petrol station has a cheap night - a time when the price per litre can sink by as much as 10 cents. That's the night to fill up. Once a week, or fortnight if you're like me and don't use the car very often, fill up your car on the cheap night - even if it's still got half a tank of fuel {that way it'll run more efficiently too - it takes more power to suck up fuel in the bottom of the tank}. Don't forget your fuel vouchers and if you've got a Coles Express like me, stock up on your milk and bread while you're there {they're heaps cheaper than a the supermarket - two x two litre milk = $5, and then if you spend a little money in store you get even more off your petrol}.
Keep an eye on your local petrol station for the prices - check whether they go up at the weekend, and down on a Tuesday or Wednesday. It will save you plenty.