Funny thing....
I was mulling over this very thing on my drive in this morning, and have concluded the same thing that LDobie and Kirwin have. Wind resistance plus power multiplication (gear ratio). I learned from towing a FW that the faster you go the more fuel you burn and it becomes exponential. Another thing that I have observed is my pals with 4:10 gears (everything else being equal) get better towing economy than I do AT THE SAME SPEEDS. Lastly, in overdrive above 2000 RPM you'll be going 70 or above and the fuel economy will suffer, BUT in 5th at the same engine speed economy increases.
Well those are just my observations and early morning musings, you make up your own mind.
Fireman
I was mulling over this very thing on my drive in this morning, and have concluded the same thing that LDobie and Kirwin have. Wind resistance plus power multiplication (gear ratio). I learned from towing a FW that the faster you go the more fuel you burn and it becomes exponential. Another thing that I have observed is my pals with 4:10 gears (everything else being equal) get better towing economy than I do AT THE SAME SPEEDS. Lastly, in overdrive above 2000 RPM you'll be going 70 or above and the fuel economy will suffer, BUT in 5th at the same engine speed economy increases.
Well those are just my observations and early morning musings, you make up your own mind.
Fireman