[ams6110]

You're talking about a series hybrid design? I.e combustion engine powers a generator which in turn powers electric drive motor(s), usually with a battery system to allow for buffering generator output and to capture power from regenerative braking.

For long distance highway driving, this is less efficient since you have losses between the generator and the electric motors. It can work well for mostly stop-and-go driving and is used in hybrid buses I believe.

[ScottBurson]

I had always thought the Volt was a series hybrid, but I just checked [0] and it turns out there's a mechanical bypass mechanism that can connect the gasoline motor to the drivetrain, under control of the engine computer. Sounds like at low speeds it operates as a series hybrid, but at highway speeds, once the batteries are drained, it turns into a parallel hybrid. Clever!

EDITED to add: dwhall posted a link with much more detail [1] -- very interesting!

[0] https://en.wikipedia.org/wiki/Chevrolet_Volt#Drivetrain

[1] http://gm-volt.com/2015/02/20/gen-2-volt-transmission-operat...