I get 50mpg plus sitting at 70mph on the motorway. In fact, I get 99.9 mpg going down hill at 80 mph, but it's not very representative of the real world.
I agree that going downhill at 80mph is not representative of real world driving, but sitting at 70mph on a motorway is. I must do at least 25% of my annual mileage doing exactly that. Going faster does cost a fair bit more in fuel..
OK, my BMW driving friend filled the tank, drove York to Middlesbrough, and back, sitting mostly at 70mph and driving steadily, thats pretty real-world driving, especially if money's tight and you are trying to be frugal. Upon returning to York he filled up and the tank average was 44.something. If a 159 2.4 should do 50+, a GT 1.9 should be doing 55mpg in the same conditons, all being well. I'm talking about real-life figures too, not OBC figs. My old remapped JTD used to return low thirties, but when I did take it for a run and went steadily it did 42mpg or so - not the best but the remap was pretty extreme and I'm sure it was still running rich.
One thing to note is that my mate used to struggle to get 35mpg, we spent a day changing the crankcase breather filter, cleaning out the EGR valve and inlet manifold, and doing an oil and filter change, which improved the fuel economy massively and immediatly.