https://en.wikipedia.org/wiki/Gyrobus
"A gyrobus is an electric bus that uses flywheel energy storage, not overhead wires like a trolleybus."
> Lots of London busses have the flywheel, it has found its application in stopping busses and getting them back up to speed quickly.
> Lots of London busses have the flywheel, it has found its application in stopping busses and getting them back up to speed quickly.