Have you put in your info on Gearing Commander
https://www.gearingcommander.com/ to see how much of a change it makes?
EDIT: There are really two contradictory schools of thought on the whole theory. One basically says "
keep the RPMs as low as possible as much as possible, even if you need to open the throttle more", the other says
" keep the throttle opening as small as possible as much as possible even if the RPMs are higher".
This thread supports the first theory -
https://ecomodder.com/forum/showthre...mpg-33961.html
I've heard that
Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering Book by Wolf-Heinrich Hucho supports the other.
It may be different for different vehicles (cars, trucks, cycle), so there may not be one right answer.