goducks10 wrote:
I always thought going faster would save gas. The sooner you get to where you're going the less time the motors running. :)
You are joking, but that is actually part of the math, a small part, but is one of the variables.
Part of variable is not the pure aerodynamics vs resistance, but with computer controlled injectors the truck will be programmed to feed fuel in at different rates depending on rpm or other variables. While the old carb engines would be predictable with increase in speed and decrease in mpg, the computer on modern trucks will interfere and make changes.
My diesel gets better mpg in the mountains and big hills than on flat. Maybe part is that I can coast downhill in N, or maybe that it is not much effort for truck to go uphill, but is way less effort to go back downhill, so net it less fuel needed.
My best ever mpg towing was I-70 in CO over the passes. I could keep boost low on climbs and just coast the downhill, or if I needed engine braking then would still not need fuel to go downhill.
