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Comment by mahboi | Hacker News Reader

That would explain it if it's large. But if this matters so much, why don't the diesel trucks make all the same resistance/aerodynamics improvements? The only EV-specific advantage there is not needing air intake... again I have to say, intake drag doesn't sound huge but maybe I'm wrong.

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The large fleet operators do care about this and do go out of their way to improve aero. Look at a UPS 18-wheeler and you'll see trailer skirts, no bug deflectors, window buffeters, etc.

Ironically, the private owner/operators are most often the ones installing accessories to make their trucks look cool and sacrificing immensely for it.

Vehicles have two primary components of resistance, air drag and rolling resistance. Rolling resistance is a function of weight, and air drag is a function of the frontal surface area (and to a lesser extent the total body surface area). For a small passenger car, rolling resistance is much lower than for a large truck, so they get much greater efficiency gains from reducing air drag. For a large truck, the rolling resistance is so much greater that the gains from reducing air drag are not large. That's why big tractor trailers don't have the same optimized aerodynamics that a tesla or a prius has.

1. No real market pressure — if you cared about fuel burn rate you wouldn't be looking into buying a truck in the first place. EVs on the other hand live or die by their battery range.

2. When optimizing, you want to start with the biggest problem and work your way down. ICEs are so laughably inefficient that improving aerodynamics just won't have that much of an impact.

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