I will give this in very basic terms, this not really brand new technology PHEV have been using very similar system for years, a more crude system is used in diesel trains. A conventional vehicle incurs between 25 to 30% transmission loses, some vehicle can be as high as 40%, the transmission loses on the E4force is considerable lower.
Whereas your PHEV engine drives the wheels when the battery is flat or in save mode – E-power is far more akin to a BEV , as the engine never drives the wheels and uses one or two electric motors to do so depending on whether its E-power 2wd or E-4orce 4wd, Just like a BEV there is no gearbox and it shares characteristics such as A & B mode and E-pedal.
I like the technolodgy and would consider an E-4orce XT 7.2s 0-62 but, with an acclaimed 44 mpg mmm!!