Nearly half a century ago, when I was in a military railroad repair unit, I worked on the forerunner of the modern hybrid.
It was a diesel electric engine that could pull a 90 car train. The large diesel engine only had six cylinders. It drove one large generator which was attached to electric motors on four axles.
About 15 years ago I got to look at one of the first modern hybrids, produced by Toyota. It was a Prius with an electric elevator motor on the driver's side and a four-cylinder gasoline engine on the passenger side. The two were connected by a planetary gear which was attached to the front wheel drive shaft. The car had a very large battery; charged by the small engine and surplus power from braking.
I watched a wide variety of plays on this engineering. Ford, called its car hybrid, which only used a large starting motor and bigger battery.
The whole issue for the railroad engine and the auto is that an electric engine begins at 0 mph with full torque.
What we have in the hybrid, since I believe all cars with gasoline engines will soon be hybrids, is a significant improvement in the gasoline engine. The addition of an electric motor means a much more level torque generating engine system as well as a more efficient energy consumer.
I consider the modern hybrid an example of the real way that new businesses are created. They are almost always evolutionary improvements.