Good Day!

My memory is pretty foggy, but I thought aero drag was proportional to the square of speed, not the cube, but if wrong, it won't be the 1st time...

From REALLY foggy memory, they used to say that the best mpg generally occurred where rolling resistance equalled aero drag, which was (for most cars) ~ 35 mph or so. At this point, aero drag was increasing so quickly it dominated mpg.

In fact, I also remember reading that rolling resistance was generally constant, & actually drops some at higher speeds. It drops so little that it's massively overwhelmed by aero drag increases, however.

I have no idea where drivetrain friction works into this.

My personal experience is that my mph drops dramatically as speed increases, which would support aero drag being the dominating factor.

Keep in mind, ALL the above is from the memory of a guy that can't remember what he had for lunch yesterday.

Keep the good ideas coming - mpg is my life.

Blessings!

Brian Johnson, # 5044