Update

 

My imaginary plug-in electric car with an internal combustion engine/generator to extend the range already exists.  (Thank you Brother David, and Jacob, and Jim and Elle.)  It was first invented by Ferdinand Porsche around 1900.  It set some records then, but hasn’t seen much use since until recently.  Currently they’re called “Series Hybrid” or “Extended Range Electric Vehicles”.  Chevy has one; the Volt.  BMW has one; the i3.

 

Electric propulsion should be the most environmentally friendly mode for these cars and should account for the majority of miles driven.  As technological gains in storing and using electrical energy continue, there will be less need for the less-efficient, and more polluting, auxiliary power, but it can always be there just-in-case.