real world MPG

[RCF]

Soooo

I'm sure this is covered somewhere but I dont seem to be able to find it in the search... So please can you all either Point me in the direction or let me have some numbers please?

I am looking at both the S4 and the RS4 as my next car... I will be using it for company business so need to strike a balance against the allowance given by my company/government vs me wanting the car

I see also the new V6 is coming down in price nicely so would like any feed back on that (MPG wise) as well if practical?

PS does it change the later/earlier model the car?
Cheers In advance
R