Flywheel powered car

Flywheels have been used for energy storage and load balancing for decades. New carbon fiber flywheels operate at 55,000 rpm and have the capability to store large amounts of power is less weight that batteries can. Major advantages are that flywheels last the life of a car with no loss of capability, they can be spun up quickly so can recharge quickly and are fairly efficient at converting power between electrical and kinetic forms. There are a number of issues including the inability to store rotational energy fir long periods and potential catastrophic failure.