You got 11-12mpg pulling TT with the 6.2L motor? You may want to evaluate how you're calculating MPG. That's simply too high.
You might get 10mpg at 60mph, but 65mph+ pulling even an empty enclosed trailer at 65mph+, you wont see 11-12mpg.
Rincon do you even own a 6.2 GMC with a 8 speed it's common knowledge they get better millage than the current 5.3 motor when pulling a trailer
My millage over 3500 miles was 18.2 via the computer running solo Highway and City combined
My trip home from the Michigan UP to the Ohio line running again 60 to 65 mph the key is staying under 65 and I averaged 12.2 mpg over those 350 miles
I have pictures of my dash spedo and millage if you want visual proof just don't know how to post here
