Well, what trooper Tdiesel said was a bit confusing to me....
As far as vans go, if you want a Ford here are your options (not including the E-series or the Econoline). The vehicle links will take you to that model's Wikipedia article so that you can see the different variants of the model, the different engine/transmission combinations and also the available cargo room (if listed). The links to the mpg are from owner's trip/tank logs, just like we do here. Be sure you sort by the engine type of your preference...
Aerostar -
MPG
Freestar -
MPG
Freda aka Mazda Bongo - MPG
Freda/
Bongo
Transit -
MPG. Be sure to sort by engine. There are a lot of available engines for this van listed.
Windstar -
MPG