I am sure that if it is driven reasonably sensible at times it would be possible to get high thirties mpg. <<<<< Never!!!
It's
possible. I once Drove a 103 Mile trip and got 38MPG overall. I started off driving in very chilled out fashion because I was hungover, and it was a lovely day, but after 20 or 30 miles it turned into a quest for best possible fuel consumption. Would have been better still if I hadn't got lost and spent half an hour driving around some tiny arse-end-of-nowhere villages near Salisbury.
Although that wasn't 'Reasonably sensible' driving, that was "pointless driving a VR6, may as well be in a 1 litre metro" driving.
So it is possible, just not particularly any fun.