TimberRunner, when you're towing on the highway how fast do you tow, and what sort of terrain? In the Central and Western US one can often run 70's and 80's for hundreds of miles with the cruise set and never touch it. Any of the modern turbo diesel's are going to click along effortlessly almost never shifting out of the highest gear even with a moderate load. That's where the diesel is so much "fun" to drive. It's 180Mi to the lake I like to fish. With my last 1/2tn 5.4L Ford ('05) I knew the 1/2 dozen places my truck was going to shift out of OD, and if I had any headwind at all, I'd lock out OD right away. Same trip with my previous '06 Ford F250 6.0L PSD or current '11 6.7L PSD the trucks would/will run in 5th/6th gear and never shift short of when I have to slow down to switch highways.
Get into parts of the US with denser populations and/or lower speed limits where you're on/off the throttle, lots of shifting, and one might notice less difference between gas vs. diesel.
