In 2019 we should see a single rotor range extender in a Mazda 3 sized vehicle, potentially even a cross over. It will function purely as a generator, much like the BMW i3 or the Chevy Volt. The engine will be mounted on its side and is a good option since it is vibration free.
https://www.engadget.com/2018/03/03/mazda-rotary-engine-returning-in-2019-as-ev-range-extender-exec/
https://www.engadget.com/2018/03/03/mazda-rotary-engine-returning-in-2019-as-ev-range-extender-exec/