My guess would be they're thinking a that running an engine to move the wheels of a car will always be more efficient than running an engine to move the wheel o

My guess would be they're thinking a that running an engine to move the wheels of a car will always be more efficient than running an engine to move the wheel of a generator, transmit the electricity, charge a battery and then move the wheels of a car. Neglecting that power plants can run at temperatures small car engines can't, getting better carnot efficiencies, or using non-combustion methods of generating electricity.