There is no way that aerodynamics account for 50% of energy use when doing long haul trucking and moving tens of tons of stuff.
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)
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%).