SS ute 14.1L/100km town driving?
Not saying you are telling porkies mate, but that's pretty damn low for stop start city driving in a v8.
SS ute official holden "combined" figures are 12.4L/100km.... but that's taking into consideration very careful driving to achieve in controlled test results. Let's say that 8 or 9's on hwy is realistically achievable by most folk. As such, to achieve the combined figure quoted by holden (unlikely but lets take it as gospel for the sake of argument) the city cycle must equal AT BEST 16L/100km. Realistic city driving by normal folk would be much higher I would imagine.
But then you've said that the 14.1L was achieved "99% city driving" (basically no hwy at all).... it just doesnt add up mate.
AFM isnt activated at low speeds, and v8's (no matter how modern) arent going to be very efficient stopping and starting in traffic- and certainly not at 14.1L per 100km. No way.
Either your fuel computer is out, or you havent reset it recently. To get an accurate fuel use, do the following:
1) fill up car as usual (note how many times you click to 'fill' and stop... 1 click, 2 clicks, whatever). Just make sure you fill as normal.
2) Drive car for 100km in the city (or as close you can get to it), and find a servo.
3) Fill car again... as normal.
The fuel you've pumped will give you a pretty accurate measurement of exactly how much juice she'll use in 100km. You can use mathmatics to get it exact (if you dont happen to find a servo at 100km), but you get the gist.
(my guess is bowser will keep pumping past 14.1L though
)