Depends what engine you have, but you'll find at motorway speeds the MPG dives off a cliff when you start sitting at 70mph or more. They're as aerodynamic as a brick.That’s actually not too bad garage told me would be low 30’s at best but what your averaging is ok! I suppose there’s a fair big tank and take about £100 to fill
On a long steady motorway run, sitting at 65 or so I can get 43/45mpg, that's on a Caravelle 150tdi DSG which is a bit heavier than a normal van.