Smaller gasoline-engine displacement and/or taller overall gearing typically provides better fuel economy, but unfortunately it also reduces engine braking. So as engineers downsize from V10s and V8s to V6s and also make high-gear even taller, there will be little engine braking in 6th gear. The only way to slow a heavy van with small gasoline engine on steep descends is to downshift in order to rev engine for added braking. That or ride the brakes which no body should want.No problems except for downshifting a little more then the sprinter. I run about 3 to 4 thousand pounds in mine all the time. Drive on a lot of country hilly roads . Plenty of power just have to give a bit more gas up the steep hills. The bad thing is coasting down hills it auto downshifts to keep at same speed.
How did you find power to be when going on an incline an how was breaking on declines?I've driven my 2500 159wb through Kentucky, Tennessee, the Carolinas and Georgia with over 3000 lbs payload. The van won't stay in 6th gear once it starts up an incline, but it will climb without a problem. Tow/Haul Mode will keep it in 5th which will drop the fuel economy down below 10 mpg, depending on the steepness of the grade. I have 22500 miles on my van. The mountains east of the Mississippi are only hills compared to the Rockies, Sierra Nevadas and the other mountain ranges out west. My 2011 Sprinter climbed these with no problem, but I am not as confident about the Promaster on those grades (I have not been there with the Promaster).
I'm disappointed with the powertrain performance. The downshift to 5th on an incline revs the engine at 3000+ rpms to maintain any speed over 55 mph. This kills the fuel economy and is just not necessary. If the grade gets steep enough, it will drop to 4th at 4000+ rpms and it will not maintain speed (it did this going through the Great Smokey Mtns coming up from South Carolina with 1600 lb load).How did you find power to be when going on an incline an how was breaking on declines?
Have you considered using the "+/-" function of the transmission?I'm disappointed with the powertrain performance. The downshift to 5th on an incline revs the engine at 3000+ rpms to maintain any speed over 55 mph. This kills the fuel economy and is just not necessary. If the grade gets steep enough, it will drop to 4th at 4000+ rpms and it will not maintain speed (it did this going through the Great Smokey Mtns coming up from South Carolina with 1600 lb load).
On that leg of the trip I was getting about 8 mpg.