@Diogenese_Shiplap You reminded me of a fascinating flywheel powered trolley I saw in a museum somewhere: It was electrically powered, but had no batteries even though it traveled away from power lines. The trolley had a giant flywheel that the motor would spin whenever it was connect to power at stops and the trolley would then tap the flywheel to propel itself.

Looking for it on Google shows that a few other vehicles also use this idea of mechanical energy storage.

@RegalBeagle The gyroscopic spinning flywheel is/was a great idea. Early attempts showed it could work, but I think there were inertia difficulties and the idea of a heavy spinning wheel below your feet seemed cost-averse. Also there wasn't the type of low-friction bearings needed to have it all work. Then the idea got shunted aside. I still think flywheel assisted vehicles hold a lot of potential, if for nothing else just to assist two tons of metal getting from zero to 5mph. That would save a LOT in fuel costs.