Half the reason I bought my A8 is that I don't do a lot of miles, so MPG doesn't really make as much difference as you'd think...
To be honest, mine will do up to about 30mpg on a run, 10-20 around town depending on how busy it is (ahem).
But hey, for the sake of 10mpg or so over some of the boring cars I've had in the past, the mere sound of the V8 is worth it. I pass through a very low railway bridge on the way home and giving it serious beans through there, windows down, convinces me of my vehicular choice every time
