True but if that internal combustion engine is only running a fraction of the time that is the savings.  How much heat gets pushed out the tailpipe and rad in an internal combustion engine.  Also its a small naturally aspirated 6 cylinder motor (presumably de-tuned for efficiency and reliability).  No turbos to crap out and 2 cylinders less than a v8.  You get the benefits of electric (torque, instant power, quiet, etc) without the range anxiety.  Diesel electric is not new tech.  Been used in rail and mining for decades successfully.  Time will tell, but I think this idea has merit.

Every time that you change energy from one to another - there is loss, typically shows up as heat.   So you will lose energy at the gen set, likely at the battery, at the power amp, and again at the wheel motor(s).     .

I had the 2024 GMC 2500 AT4X and now have the 2025 GMC 2500 AT4X both with the 6.6 gas.  No issues with plugs or oil in either.

Similar tech for big rigs   https://edisonmotors.ca/  

More efficient use of power also.  No power loss through transmission.