I face a massive dilemma!

Want to change my car and it's gotta be an A8. Everything is fine great about the S8 apart from how much fuel it drinks. Insurance doesn't even vary much between all models including the S8. And parts are hardly going to be dearer on an S8 are they!

But bear in mind what fuel costs in the UK (Near £5 a gallon) and you'll see why it would hurt to run an S8

Looked at and driven a few S8s now and love them, but went to see this today and is it a good compromise? 2002 2.8 Quattro Sport

Ok, from what I can see I'm gonna miss double glazing (Will road noise be noticable now?)
No Rear blind or side blinds
No sat Nav
And of course the performace drop is considerable. But how much in the real world. I do a lot of single carriage way passing and so it'd need to be good at kick down at 50-80mph

Bonuses..
It's a late 2002 model where I'm looking at a 1999 tops S8 for the same money
Xenon headlights
Those 'to die for' wheels
Better economy from the 2.8 V6
Lower mileage