It seems an impractical solution for a car, and better used as a massive and immobile mechanism where you can trade out a lot of that velocity for mass, and where your housing isn't actively fighting the storage the whole time. I would love for someone to do the math on how much kinetic energy you'd need to store in a wheel that can fit in the engine compartment to allow a 2 ton vehicle to go 200 miles in stop and go traffic.

Not all energy storage solutions can work in every problem. We won't be using hydroelectric for cars either.