I'm most intrigued by the Mazda range-extender concept...similar to a PHEV with a simpler engine that charges the battery/delivers electricity to the motor. Might be best to just skim this article but read the comments in this article:
https://www.theautopian.com/the-rota...r-on-the-road/
Unlikely this first iteration will be a panacea, and I wonder how much room for improvement exists for what is essentially a portable generator, but it'll be interesting to see the IRL specs on this.