They're interesting figures... don't know how you came up with those mate.
I've got the SS V Ute / Manual
Thrashing the ute occasionally I'll get about 400km a tank - thrashing it all the time... around 350km bottom line. Basically it'll average around the 17L per 100km when you want to give the car stick all the time.
Commuting and highway driving is great, more economical than my parents VT V6 sedan. Stop start traffic will bleed you around 14L per 100km on average if your mildly accelerating and the occasional thrash to get around Grandpa behind the wheel.
The best scores I've had so far is 596km (630km without load - explain later) on one tank and that was at an average of 11L per 100km but that was purely highway driving (helps if you're travelling from Melbourne to Darwin which I did recently lol) and that's from absolute full to absolute dry. I conked out just as I was overtaking a 4 carriage 50m long road train... yup I reckon that was smart when I had to pull over just up ahead in front of him and get the 20L jerries out. Oh yeah and the top range figure was also carrying a 200kg load in the tray + trailer with a 200kg motorcycle on it.
As an owner, expect an average run of 550km range off a full tank ($75 - $95 depending on fluctuating petrol prices) and an average bleed of 13L per 100km if you mix it between stop-start traffic and highway driving.
All in all even with the AFM tech coming up, the V8 engine put in the SS models do really well on the petrol compared to the V8's of old and even V6's. I'm more than happy with it.