[slowmover]

Average speed is in signature.

I've noted that FE is good in a CTD where the average speed is at least 26-mph. Below that it drops like a stone for a given truck specification (to cite variances in vehicle spec, climate, terrain and driver skill).

Asking this question on CTD forums has tended to confirm this average.

I suspect it is true for nearly all other automobiles as well.

As lower highway travel speeds are conducive to highest mpg (above 60, is, literally, speeding), so, too, is the elimination of idling conducive to highest average mph (no drive thru's, no idling for interior temp regulation).

One might look at average mph and long-distance travel speed as ideal where they are numerically closest together.

How to do that is known as a "trip plan".

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