Are you suggesting to use flywheels as an energy source in EVs??? There is a heap of issues with this idea, the main ones:

- They are VERY heavy. Typical energy density for flywheels is 10-40 kJ/kg (if you account for the whole flywheel), while Li-ion batteries and gasoline store 300-1000 kJ/kg and 46700 kJ/kg respectively (the latter does not account for ICE efficiency).

- They are relatively big, since you can store more energy with a bigger diameter (limited by material's strength-to-weight ratio).

- Flywheel is a big gyroscope. You do not want to rotate it around while it spins.