I have a 2006, 118" wheel base, low roof unit. It has 110,000 miles on it. i use it for daily work, and to tow a 20 Ft enclosed pace trailer to and from the races on the weekends. I would say the mileage is about 20% with trailer.
I have only had a one minor mechanical issue with the van- (blown resonator) I'm on my second set of tires.
I track my fuel mileage on this site:
Gaslog data for Dodge Sprinter Van
I am still looking for ways to improve mileage. (slowing down not being one of th choices)