I smashed my previous fuel consumption record (552km from 63L = 11.4L per/100km). It now stands at 622km from 60L = 9.6L per/100km, I could have pushed it to up around 640km but I didn't want to risk it because I was about to turn onto the M2 and wasn't sure where the nearest servo would be off any of the exits hehe.
I got the 622km just by driving from Penrith -> Canberra -> Penrith -> Seven Hills. I was using Shell Optimax with a standard airbox, standard airfilter, standard turbo, 7psi boost and it was pretty much about 550km of pure 110km/h highway driving (5th gear doing 110km/h @ 3,100rpm) and 72km of normal driving (happy laps around Canberra Summernats). and 1 extra passenger with luggage (around 160kg more than I normally carry).
I'm pretty happy with that result because its still only the standard ECU so with a PowerFC and a good tune im sure it would go beyond 650km but I won't know until 2005 when I go to the Summernats again hehe.