Fuel consumption by Fiat Ducato

[Rog Wilko]

We have a 2005 2.8 td 5 speed van conversion and reckon to get about 32mpg driving conservatively. We are thinking of changing to a newer van and I understand that since about 2007 most motorhomes are built on a 2.3 td model with a 6th gear. I'm just wondering if economy-wise this is an improvement. Does anyone have experience of driving both the 2.8 and the 2.3?