what are automobile flywheels made of
6.6 Materials for Flywheels. Flywheels store energy. Small ones the sort found in children's toys are made of lead. Old steam engines have flywheels; they are made of cast iron. Cars have them too (though you cannot see them) to smooth power-transmission. More recently flywheels have been proposed for power storage and regenerative braking systems for vehicles; a few have been built, some of high-strength steel, some of composites.