MPG vs MPH vs Cruse Control

[vernj4]

Some recent observations:
1) tires for my TT are rated at 65 MPH
2) I only use cruise when on FLAT pavement
3) Goal: keep speed between 55 & 60 MPH, regardless of terrain.
This means I set the cruise at 60 MPH if on FLAT pavement. If in hilly area, I let off the
accelerator when going down a hill and at least try to maintain 55 MPH when going up
hill.
4) On a recent trip going to AZ, we averaged 12.93 MPG. On the return trip to MI, we
averaged 13.60 MPG. This was while pulling a 8377# TT.
5) The trip was very relaxing!

[DickWells]

Good stuff! Lines right up with my own observations. IE, unless you're on flat going, solo, or towing, your foot is much more sensitive than the CC, and is able to monitor the throttle opening to a much better degree. You can even anticipate a hill, when towing, and get up to even higher than 60 to keep the trans from down-shifting. I can pull some hills of up to 6% or so without a down-shift, or going above, say, 14PSI boost, where in cruise, you'd go to maybe, 24-2600 RPM and 17-18 PSI.
You're getting pretty darn good mileage, towing! I haven't averaged over 12 mpg since Summer 07, going to Alaska. My trailer weighs right at 11000, though.

[rustyk]

My DP motorhome clocks in (usually) around 15,500 lbs. With the AMG engine (non-wastegated turbo), I average around 11 mpg, pushing a lot more frontal area than you have.

I found the CC makes the tranny too busy. I have the TPS set way down, so a downshift is rare. I can pull 6% in 3rd at 50-55mph, boost at around 12 psi, EGT around 900-950°.

[vernj4]

Personal unit is a 32' TT. Recently pulled a 38'-6" 5th wheel 600 miles. This unit weighed in at 10560" and was 12'-10" tall.

Goal was to keep the speed between 55-60 mph w/o the aid of the CC. The fuel mileage was calculated to be 10.70 mpg. What a difference the height made. Pulling that large sail around cost approximately 2 mpg.

The return trip (no load) allowed us to get 21.52 mpg at 65 mph. Very respectable mileage and inline with our overall experience.