I clarified in the first post that the 18 miles is just one way.
Regarding the EV-versus-ICE efficiency on ascents/descents, one way to look at it is that it took (in this instance) about 3.5x more energy to make the ascent than the same distance on flat ground. Such a factor would seem to apply regardless of EV or ICE.
Of course on the descent, the best an ICE can hope for is zero fuel burned; realistically there will be *some*, maybe 0.1x of the flat ground cost (wild guess there).
So the ICE total/average comes to 1.8x for the round trip. For the EV, the descent 'cost' -1.25x the flat ground cost (i.e. negative cost), so add that to the 3.5x for the ascent and divide by two to get just 1.125x for the round trip (a 38% improvement over 1.8x).
Pearl White 2016 Leaf S, 24kWh battery
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