Have I been doing it wrong all these years?

rollexx wrote:
I have been towing our 30ft fiver for years with a Silverado 2500 Duramax. Have been using the tow mode and get right around 12MPG. Today we headed out. I zeroed out the trip computer before leaving. Stopped at a rest area about 100 miles out, all freeway traveling at about 60 as usual. It’s then I noticed I had forgot to put it in tow mode. Checked MPG reading and was surprised to see 15 MPG. Tran temp and engine temp were normal so just left it off the rest of trip, another 140 miles. Checked again at end and got 14.4 MPG. So my question.. On fairly flat highways should I leave towing mode off and only turn it on when I hit the hills?

Had an 01 Sierra with the Duramax. I found it held the lower gear on flat roads so I'd turn off the T/H until it shifted and then turn it back on. Once in 5th, it would stay there with T/H on. But I liked T/H for getting up to speed and hills.

I doubt it would be a 3 mpg difference though.