[vteco]

Well having read through the 100+ tips here I can say truthfully that I am already driving that way, nothing seemed new, and particularly I've been maximizing since the Subaru has instantaneous and trip average MPG readout which I've paid careful attention to for the last 6 months.

Nevertheless, the Subaru, just tested a half hour ago on a 10 mile round trip down the mountain and back, will slow down with the foot off the pedal on even a moderately steep downhill grade. I'm thinking this must have something to do with the "all-wheel drive" being computer apportioned somehow during coast.

The Silverado easily and rapidly accelerates on practically any downhill grade, pedal off. While it has 4 wheel drive, it's only when manually engaged.

This is a separate issue than wheel inertia.

I think it's not established that "wheel inertia tends to be troublesome for overall efficiency" in my own case since that overall efficiency is composed primarily of winding hill conditions, with little highway usage.

I'm going to guess that:
80% of my driving is up and down winding mountain roads at 35-45 mph speed limits
12% hilly town streets, 25 mph speed limit
5% hilly 55 mph highway speed limit
3% hilly 65 mph highway speed limit

These conditions probably have their own set of optimization scenarios. That's what I'm interested in. I think that will take an open mind to work out.