the speed reduction from the electric motor is handled by simple fixed gears and computer control of the motor speed.

Yep. And if you use asyncronous motor or synchronous reluctance motor it is also extremely cheap and reliable, since the only copper is in stator windings, there are no expensive rare-earth magnets and there are no brushes. Also, electric motors have high torque at 0 RPM, so no any need for clutch.

Now as for the power, we are still waiting for Doc Brown to release the Mr Fusion powerplant to use instead of batteries.

Power source should be of same simplicity, reliability and cheapness, and there could be huge breakthrough in our means of transportation.

And if we are talking about Doc Brown, the flying option will be necessary too. It is much easier to fly even, on some small old Cessna/Piper/Beechcraft, than to drive the most advanced car. :)

PS: IIRC, Doc Brown didn;t invent Mr.Fusion and flying option, he upgraded car in the future. And since his future with flying cars and other stuff was in 2015 we are definitely in some wrong and weird timeline.