Gyrobus rings a bell!

Flywheels are very interesting.

Buckytube composite super high strength spokes
and super dense super strong depleted Uranium flywheel rims
would be a new “twist” on an old invention.

Last time I thought about flywheel science on moparts
was when discussing how to measure the power losses to friction
inside transmission, driveshaft, u -joints, differentials and axles.
for not much money.

I originally thought this required expensive special equipment,
but some engineers showed how to do this on the cheap:

Wheels with tires are “flywheels”.
Wheels filled with water instead of air are flywheels that store more energy at the same RPM.

jack the rear of a vehicle up so the rear wheels are off the pavement.

Run the “up in the air” drivetrain up to some speedometer reading like 50 MPH.
Time how long it takes to coast “in neutral” to a lower speedometer reading like 10 MPH.

Do this at other speedometer readings like 70 MPH coasting down 5 MPH.

Repeat with wheels filled with water.

This creates multiple equations,
multiple coast down times,
and can be mathematically solved to find
multiple “unknown friction percentages” for transmission losses, differential losses, etc.

One last “tricky” step.

You need to know the “Rotational Inertia constant” of these tire flywheels,
commonly called Ir.

Ir for an air filled tire will be a lesser amount than a water filled tire.

You can measure this Ir in a simple cheap tricky way
by rigidly attaching a long, but very thin diameter threaded steel rod to the center of a wheel using two nuts,
then rigidly attaching the other end of the threaded steel rod with two more tightened nuts to something high up
like a
garage ceiling,
basketball goal post, etc.

A small threaded rod 1/8 inch to 1/2 inch diameter
and 60 to 72 inches long
is typical.

The thin rod is scientifically a
“torsion bar spring”
just like Mother Mopar was fond of.

Have a stop watch ready to time.
Get the right size Torque wrench.

Use a torque wrench on a bolt to twist the wheel 90 degrees,
write down the torque,
then let go by quickly pulling the torque wrench off while starting the stop watch.

The wheel will now do the “wiggle twist” dance
rotating back slightly less than 180 degrees,
come to a stop,
begin a swing back less degrees than before to the other side,
come to a stop,
reverse direction, and so on.....

Stopwatch time 6 to 12 of these oscillations.

There is a physics formula to calculate the Ir of the wheel
from the torque first applied and the time to do one oscillation.

Old fashioned wind up wrist watches had an oscillating flywheel like this inside.

Now repeat with a water filled wheel.

Repeat with a wheel filled with calcium chloride saturated water, etc.

Or just repeat with heavier wheels or bigger heavier tires.