We are are on the last leg of a 9000km trip from flat Saskatchewan through the Mountains in Oregon, I have the speed brake and Econo tuner.
Speed brake, once I figured out the speeds for the 1st,2nd and 3rd speeds, I rarely had to use the brakes on long down hills. Has anyone done the July 4th pass or the climb and down hill from Idaho to Montana? I worked great. On the down hills I hardly touched the brakes. Works bettee than I could have every imagined.
Econo tuner, I have it set on number 2 econo. here are some stats to digest. Last year pulling the our 5th wheel SOB same weight same road (except for a detour due to wash out which has many hils) from home to Lethbridge alberta about 650km we used 200litre of fuel, this year with the detour we traveled 729km and used 167 litre of fuel. Yesterday we left Missoula and traveled to Medicine had through the glacier scenic road (many hills and a few passess) 751 km we used 151 litres of fuel, we did have a bit of tail wind for one part of the trip.
I find the tip to fuel economy with our 07 LMM duramax is 55mph and six gear. If anyone has trouble getting into sixth let me know there is a trip to it.
when I get home I will submitt my mileage calculations. Gotta go DW just texted that she is ready to roll.