Ok it is not a Golf but my 170BHP engine had me achieve 52MPG on mainly Motorway trip yesterday with some bursts of speed on M and A roads when opportunity to, if babying imagine near 60 MPG but that never going to happen! - Normal use is 45-50MPG and if pushing it around 40-45 MPG so unless the 184BHP is engine is worse which by figures provided it should not be (and Monkey comments on his Dad GTD) then I see that 60MPG as very reasonable and 50MPG my low figure which is not a lot of fuel for having some decent fun in
I agree with comments here that if doing low mileage and it is a private and not lease/company then GTI all the way as there will be a difference but not as much to justify not going for GTI.
Company drivers with incentives for C02 and likely with higher mileage then the performance/ecoonmy balance in GTD is a no brainer also.
Not going to dispute that GTI has real driver pleasure but GTD is in same suit and do not underestimate the power in day to day driving that it delivers - All I can say is my present is far from a slouch and when pushed brings smiles every time so yes I might lose a drag race now and again but for most part my experience is going to pretty damn good