Originally Posted by Twisty
From what I've read, the extra MPG goes away very quickly if you can't keep your foot out of the throttle...
I've averaged just about 10 mpg towing our Roo 23SS with my Eco supercrew with 3.55. It's more dependent on wind direction than throttle position for me, though.
That said, I recently upgraded to an Android phone so I got a bluetooth OBDII adapter and the torque app. We just got back from a weekend trip to Key Largo and I experimented on the way down and back. The results were a little surprising. My best cruising mileage came with 6th gear locked out and with tow/haul turned on. I got 11.5 going down and 11.1 coming back. It runs at about 2100 rpm in 5th and only 1800 in 6th at 60 mph, but 6th requires 8-10 lbs of boost where 5th only pulls a pound or two.
Our next trip isn't until August, but I'm definitely going to keep using Torque to try to find that sweet spot.