I typically assumed in vehicle energy efficiency debates, the importance always in propulsion- to reduce vehicle mass. This usually implies high energy mass density fuel, like hydrogen fuel cells, gasoline, super capacitors or something similar. Interestingly, lithium ion is not so good.
But then I realize we operate in atmosphere. So it seems in real world it could be plausible that heavier is better. I guess the idea is that energy is stored as momentum. And perhaps improving the vehicles momentum, reduces the parasitic, constant loss of energy due to air drag. So then there would be two competing constraints, to reduce mass, and also increase mass, and then with additional things. Such as the idea, fewer topology per volume, may reduce mass further. Kind of like say 8 small engines vs 1 giant cylinder. The topology is optimized with 1 cylinder.
So my question is how does mass reduce air drag energy loss if it even does? Perhaps it relates to ballistic coefficients?
One supporting observation to support asking this question would be that larger tanker ships are very efficient then smaller ones. Making analogous the issue with a ship in water rather then a car in air.