I'll share my tip about how I save fuel.
If you have a VT/VX with the single-window trip computer, set it to instant fuel consumption (hold down "Mode" and "Up" on the computer while you start the engine, then press "Mode" till you have some numbers and "L/h" next to it)
This works twofold for me,
1) Simply having big numbers flash before my eyes when I floor it helps me calm down and ease off a bit!
2) I often set myself a goal of 10L/100km, and trying to stick to that helps save a lot.
!!! Important !!! 10L/100 doesn't mean the display reads 10! For some reason Holden thought putting the display as litres per hour instead of per 100kms would be a good idea, but its easy to work it out; basically if you're doing 60kms, the window should say 6L/h, if you're doing 85kms it should say 8.5L/h etc etc.
!!! More important !!! You will rarely be able to achieve a goal of 10 whilst accelerating from lights, but if you accelerate modestly and try to cruise at <10 you should be able to do quite well. Also be mindful of other drivers, and if the situation requires, give it a bit more. Don't be one of those assholes who sits in the overtaking lane going at the same speed as a the left hand lanes!
I get 11.5-12.5L/100 like this, all city/suburban driving.
Obviously your results will depend a lot on you're car too. I know for example when I changed my O2 sensors I dropped about 2L/100! Its always worth keeping your car tuned up.