I'm always underwhelmed by the 4 cent per litre discount vouchers offered by the supermarkets.
On our fill up yesterday, we saved the whopping total of $2.04 on our $100.94 petrol purchase, thanks to a supermarket voucher.
Dick Smiths have gone a bit higher with their discount - 49 cents per litre:
I've been using Fuelly for the past few months to track our fuel spending. I don't know that it's providing a lot of value, but it is cathartic to process my receipts as if it's somehow helping :)
Kirk