I managed to get 640 kms out of a tank before the red light started to glow full time, was starting to flash at the 600 kms mark. Trip computer said I could still do 95 kms. Standard unleaded BTW.

A Mix of some city driving and the rest was highway (270 kms from Bunker Hill to Howlong, NSW, then about 20 kms around town, then 330kms back to Cheltenham). Car took 60 litres to fill again.

Average fuel consumption all up was about 9.37 L per 100kms - is that good for a car of this size?

Also, the fuel gauge seems to vary sometimes, like I could travel (from full down to 3/4 full) and cover 200 kms on the highway, but manage almost 150 kms around town. From 3/4 to 1/2, I could only do 110 kms around town and 170 kms on the highway?

Only for I6s.. Bah, too bad. I'd say they're exactly the same between V8s and I6s. They are not really accurate at all, so refer to the clock instead. When you fill up, it will stay around "F" for quite some time, then after that it will drop dramatically.

Perhaps Ford did that to make drivers drive economically and/or make sure they don't run on empty as that kills fuel pumps.. Who knows.

I notice this also, once filling up i always drive for day or two thinking "sweet, getting heaps on this tank of fuel" but once it gets half way thru the 1st segment its all over, it drops like gravity is taking over.

yeah, it's definately not linear.

The first quarter tank last me over 200Ks, the other 3 quarters about the same (i get between 400-450K per tank).

well I got 70kms off a quarter of a tank driving on the highway today? accurate? hell no.

Cam,
as said i believe the gauge isnt linear also i got 300kms out of half a tank by the gauge - the rest lasted 150kms!