I wonder if mine is down on MPG due to 4Drive? I average from new 28.6
It's hard to say 100% without knowing your driving profile, mine never really does town work, but likewise never motorway.. it's lives on B roads but then it gets used properly!
In comparison to other stuff I've owned with the same profile this Cupra is very very good on fuel.
The 4drive will 100% not
help though, you're carrying substantially more weight and drag, my mates has a Golf R and his average is 27/28 and his driving is pretty much identical to mine. ~5mpg difference sounds about right to me.