Oasis-3, Your mileage and records speak for themselves. Had no idea the fuel would perform this poorly compared to LSD. I also have no explanation for the near 10% mileage drop you're seeing. ULSD is supposed to have 1% or 2% less energy than LSD... not 10%.
A big engine pulling a load is going to be more telling than my little Jetta. I could have easily missed a 1% drop in mileage (53. 5 mpg vs 54) but 8% would have caught my eye right off the bat (49. 5mpg vs 54mpg). My last road trip (the Jetta now. . not the Dodge) of 1200 miles on ULSD netted over 50 mpg @ 75mph which is darn good even for the thrifty Jetta.
My wife and I are about to make another trip from southern Cal to Austin Tx. It's about 1400 miles (Interstate 10 all the way) and I'm in no hurry this time so I'll set the CC on 65mph and keep track of the use. The Jetta consistently gets >54 mpg at that speed so I'll report back in with the results.
Keeps us up-dated, if you can, on your results for '07. Anyone else out there keeping records like this? Let us know your findings.
Mike