As far as fuel mileage goes. I can tell you this about an 2013 Golf R.
It gets as good or better mileage in pure city driving as a standard WRX which is about 19-21 mpg if you never see a freeway and on run light to light.
I have not put a road trip on mine yet, so I do not know what it would do, but when I run into Houston a couple of times, I routinely get mid to high 20's
I got 16 mpg in my 2006 STI in pure city driving..
What fun it was though.