One thing I really like about Ford and Toyota hybrids, is the transmission is actually simpler than a pure ICE vehicle. I haven't found that many good write up

One thing I really like about Ford and Toyota hybrids, is the transmission is actually simpler than a pure ICE vehicle. I haven't found that many good write ups online, there is one fairly good youtube video (it covers the Toyota implementation, but Ford's is similar). The transmission consists of one planetary gearset, and two combination motor-generators. The engine is hooked to the planet carrier, the wheels and a larger motor/generator is hooked to the sun gear, and a second motor/generator hooked to the ring gear. When running on the ICE motor, the smaller electric motor acts as a generator. By varying the amount of current going to the larger motor (and/or battery), it effectively changes the gear ratio. When running on battery, the larger motor is used for motion, and is also used for regenerative braking. The smaller motor is then kicked in at a different speed, to start the ICE engine when needed. Of course, the complexity is all in math that drives the software, but there is much less mechanical complexity in that transmission (compared to an automatic, and even to manuals). But the end result is a very smooth acceleration that seamlessly moves between electric and gas as needed (the feeling is pretty close to what you would get if it was all electric).