My first thought is that nearly everything posted by NewAtlas is garbage. Certainly all of it is just taken from another online source, in this case CNET, which got everything from the company's marketing people.
Reading the title, my next thought is that it is not possible to "massively" increase the efficiency of electric motors, which are already quite efficient, so the claims are bull. They mention a 20% increase in efficiency, but anything over 84% efficiency, a 20% improvement would be better than perfect efficiency... yeah, likely.
About half of the points in the explanation are just nonsense.
There might be something to the idea of massive pole areas for lower flux density, allowing for cheaper permanent magnets. But then, some conventional motors in hybrid vehicle applications use ferrite magnets, too.
Your calculation is for a 20% reduction in loss, which is not what they claimed at all. A 20% increase in efficiency from 80% efficient would be 1.2 * 80 = 96% efficient... which has zero probability of being true.If a motor is 80+ percent efficient, a 20% improvement would bring it to about 84%.