Assuming your truck does 60 mph, it appears it does[1]. 80Hp for rolling resistance, electrical and all other losses, 120Hp for aerodynamic drag.

Of that, cars modified to be super efficient (eg. [2]) can get the Cd down to about half (from about 0.31 to 0.17). Trucks could probably achieve an even greater improvement, because production cars already have a slanted windscreen and rear trunk.

So, overall, I stand by my claim that energy use of trucking could be reduced by about half with aerodynamic techniques.

[1]: https://theicct.org/sites/default/files/publications/AERO_RR... (figure 2)

[2]: https://www.aerocivic.com/

If you cut half the air resistance and air resistance is 120 out of 200 hp, that's only a 30% total reduction.

halving aero drag != halving fuel consumption at the speed EU trucks are limited (55mph): https://www.researchgate.net/figure/Figure-11-Fuel-Economy-w...

Trucks in Europe are not allowed to travel 60mph.

True, they have to do kilometers per hour over there.

You're right because internal combustion engines are so inefficient that more than 50% of energy is wasted before it can even contribute anything. But in terms of useful energy leaving the engine it's a different question.

Once you get to long-haul speeds, the energy cost is almost entirely split between air resistance and rolling resistance, but air resistance has the edge, (about 50%), rolling (30%), drivetrain (5%), and everything else (10%).

After you've accelerated the truck to highway speed, the weight only matters due to friction. The friction and aero costs are large enough that the acceleration cost doesn't dominate.

All these assume flat terrain. As soon as you start adding hills things look completely different. That's the one reason why I think e-trucks make sense, the ease of regeneration rather than burning off the momentum as heat.