The FE (Fuel Economy) of your van may benefit from this thread:
http://ecomodder.com/forum/showthrea...you-15182.html
(Edit: The next paragraph is false. The van gets higher economy between 55 and 65, Coasting. Do note at which point you get the best economy, Though.)
I've noticed this too; When on a flat (Generally speaking; There are many hills and slight inclines where I live) If I'm going 35 MPH/56.327KPH I get higher FE than at 45 MPH/72.4205 KPH. Going 65 MPH/104.607 KPH on a highway over 55 MPH/88.5139 KPH really kills the FE even though the ScanGauge II isn't calibrated properly yet.