V8 and V12 mpg & BMW Ownership

Hi,

I'm looking to move up to a V8 from my current Volvo T5 (240hp). I am
considering the following cars:

BMW 535i V8, 540i V8 (4.0) and 540i V8 (4.4)
BMW 740i V8 (4.0 & 4.4), 750i (V12)
Jaguar XJR 4.0 V8 Supercharged
Jaguar XJ8 4.0 V8
Mercedes S-Class V8


Although not overly concerned regarding miles per gallon, I am just
interested to see what you get on your BMW V8's (or V12's) in real
world driving. I am from the UK (hence the 535i being a V8). As a
basis for comparison I get 30mpg cruising and about 19mpg town out of
my 2.3 I5 Turbocharged T5.

Also, what is the BMW ownership experience like? Why did you buy your
V8 BMW and would you buy another?

Many thanks,

M.Jordan