I just broke 520
Check my signature, it tells all! 520 before the gas light came on (not steady, just poped on then off) out of 12.522 Gallons in my 06 stock forenza. Unfortunately my digi-cam crapped out I did have a pic of it at the gas pump. I'll grab one next time.
The only thing I do not do that most hypermilers do, I don't kill my engine. I tried it a few times, however on my Forenza it seems to use more gas to start it, or to even pop the clutch than it does for me to just idle around.
Feather the gas, keep RPMS under 2500, shift at 2500 and coast downhills with the clutch pressed is really all I do. Oh and slipstream trucks. Not exactly safe being 5-10 feet off their bumper, but I won't argue with coasting behind them for 10 miles without using much of my gas
I concur with the first post, stay on top of your maintenance, it will help regardless if you hypermile or not. Slow and Steady is the ultimate key when it comes to driving. Practice keeping your foot steady in one position for half an hour, it makes life easier to remain constant while on the roads if you don't have cruise control such as I don't.