Updated - over 25,000 miles now. 19 MPG seems to be working. Bone stock. 2500 HD CC.
http://home.columbus.rr.com/vfrket/Diesel/Diesel.xls
Note my calculated Miles Per Hour (miles for the tank divided by elapsed time (hours) from the from the DIC) to the far right. BTW, I still like my spreadsheet. There are few rows of data where I had to add a couple tanks together.
Kelly