[Happy Monkey]

The article is about boats; I'm mainly thinking about cars:

For one thing, the diesel engine is not directly hooked up to the wheels, so at least one part of the question really is whether all of the components between the diesel motor and the wheels are more or less efficient than the equivalent for the electric motor. Every moving piece is lost power, and an electric motor doesn't need a transmission. This is before all of the complicated analysis in the article, which, if I got the gist correctly, is primarily concerned with the decoupling of engine/generator speed and motor speed, allowing the generator to operate at ideal RPMs for efficiency, while supporting a range of speed/power combinations on the motor.

Add a battery, and you can save the energy that a diesel engine otherwise would lose when idling. Add regenerative brakes, and you can also save the energy otherwise lost in heat and brake pad degradation.